In general, a pressure lube system is superior to a splash lube system, especially when the engine is subject to running on inclines. The pressure lube ensures much better lubrication of critical engine components. However, there are some applications where a splash lube system is adequate.

Splash lube = Yesteryear's engine lube technology...

Pressure lube = Modern engine lube technology...

Guess that says all thats really needed... hehe
Paul R...

Pressure lube is superior to splash lube because the oil is delivered directly to the loaded side of the bearing surface of the engine component in high volume. The actual amount of "pressure" per se depends on several factors such as: Clearance between the 2 components at each bearing surface (age and wear affected), engine RPM (operator affected), and the pressure relief valve in the oil pump (OEM preset). The fact that the lube oil is delivered precisely to the load bearing surfaces enables the oil to support the components on a "hydraulic pressurized layer of oil", minimizing metal to metal contact. Splash lube systems depend on the viscosity and film strength of the oil to bear the loads. Because the oil must first get into the bearing surfaces, viscosity has to be correct. If it's too viscous, it will not adequately enter between the 2 bearing surfaces. If it's too thin, it will just squeeze right out when the load is applied. Either extreme can result in excessive metal to metal contact, which engines do not tolerate well. The biggest BONUS to the pressure lube concept (as used in modern engines) is the "full flow oil filter". In the full flow system, every drop of oil that is delivered to the bearing surfaces, has been filtered (unless the filter has reached it's entrapment capacity because the filter has been neglected). In splash lube systems, the oil and all suspended particles is thrown into the bearing surfaces, grit and all. Any more doubts?

The splash lube with oil filter is a low buck (for the OEM) way to add filtration without going the entire route of building a full flow pressure lubed engine. The splash lube with filter consists of an oil scavenging pump that sucks up oil from the sump (along with debris). The oil is then routed through the filter where particles are captured. After the oil is filtered it dumps right back into the sump. This technique is a step better than plain splash in that some harmful particles are removed so the oil is cleaner throughout it's useful life (instead of continuing to get dirtier and dirtier with time). You still don't get the benefit of the pressurized oil bearing the load as you do with a pressurized lube system.

I am still waiting for someone to post about their 40 year old tractor that still purrs like a kitten with splash lube after all these years (as though that has any bearing on comparing two tractors in todays market) : )

Outside of a lower up-front cost, is there any reason to want a splash lube system? As far as I can tell, it would seem pressure lube is superior in all other regards.

Pressure lube is far superior in terms of engine longevity. An engine manufacturer can basically add a scavenging filter system to an "old mold" engine, do some cosmetic sheet metal work, tack on some plastic jewelry and sell it as "new tech goods". I would dare say that a lot of prospective buyers looking at the machines lined up on display wouldn't have a clue about that oil filter (if they even noticed). Having an "oil filter" in place gives the OEM, and the sales people something to pitch. As many folks in the forum have pointed out some other "tricks" used by OEMs to drive the price lower to meet, or challenge the market, I consider the scavenging filtration system to be just barely more than a sales pitch or marketing ploy. Yes, some of the oil gets filtered all the time and eventually (in theory) all the oil gets filtered, but you don't get any of the benefits of supporting the bearing surfaces with pressurized oil. And that ain't no gimmick.

Sadixon49,

You mentioned the Briggs engines used in Craftsman equipment. All the single cylinder Current ELS engines are equipped with full pressure lubrication. Other models of the same engine that are not ELS are probably the splash lubrication version with oil filtration.

All the V twin engines have full pressure lubrication. I have observed some V twin craftsman mowers with the oil filter deleted. While the engine still has pressure lubrication, there is no filtration. Deletions like this are usually requested by the equipment manufacturers or Craftsman.

Thanks to all for contributing to my understanding. I think I knew some of this, but you read so much of the "my engine has run 40 years without pressure lube stories, that I was beginning to doubt myself.
thanks again steve

Either systems require routine maintenance schedule based on conditions the equipment is used in, splash of course is more often. Don't change or check the oil and see how long the last?

Air cooled carbureted gasoline engine = Yesteryear's engine technology...

Liquid cooled fuel injected engine diesel = Modern engine technology...

hehe

Posted by metal (My Page) on Fri, Jun 15, 07 at 17:36

I am still waiting for someone to post about their 40 year old tractor that still purrs like a kitten with splash lube after all these years (as though that has any bearing on comparing two tractors in todays market) : )
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OK..... since you requested, I will comply. My 1972 Kohler K powered Case still purrs like a kitten and it's 100% splash-lubed and 35 years old. Close enough?

As for it having relevance in "comparing to tractors in the market of today"...........yes and no. The metalurgy today is vastly superior to the metalurgy of the fifties, sixties and seventies. In addition, lubrication technology is also dramatically different. So, we can't really compare the engines of today to the engines of yesteryear because it's not an apples to apples situation.

Without question, pressure-lubrication has its benefits, especially in overhead valve engines where splash lubrication finds it nearly impossible to properly look after the valve train. Realistically speaking, the new generation of splash-lubed engines are better than the old ones but the old ones can be rebuilt easily and economically. Many of the new engines are considered to be throwaway because the cost of parts and labour often exceed the cost of brand new short-block at minimum and sometimes even a long-block.

But to me, all of this is rather moot because the funny part of the whole argument is that damn few of these posters who seem to overthink and worry about this issue, won't even keep their tractors beyond the ten year point. At an average of fifty hours of use annually, ten years is a mere 500 hours. Big deal. Either type of engine will easily last 1000 hours if the owner just changes the oil and filter on schedule.

So, all of this angst over the lube system of the engine is rather silly in the context of normal ownership periods. And as I have said in previous threads on this very topic, either of these engines will likely be running just fine when other parts on the tractor itself start failing.

For the purposes of powering OPE, there isn't a thing wrong with engines that use splash-lube. They will perform just fine. As for this tired old claim that splash-lube engines run out of lube when mowing hills, well that's a load of crap. If the grade is that steep then the tractor shouldn't even be on it because it isn't safe. Even a pressure-lubed engine has its limits when it comes to the tilt factor. especially when people don't keep the crankcase full.

Castoff! Thanks for your comments.Theres hope that my LA100 with the splash and Lube will have a decent life.

Pressure Lube compared to Splash Lube is like Carb intake compared to EFI fuel delivery.
New technology vs old, sometimes its better, sometimes it ain't.

To reiterate a well worn concept: Please change the oil as it needs to be! And whether it is splash lubed or pressure fed, KEEP THE RPM CLOSE TO GOVERNED SPEED when engine is loaded. Running engines at low RPM when loaded allows the oil to be displaced from the bearing surfaces faster than it can be replaced. This condition is called "lugging the engine". If your load is so great that the engine begins to lose RPM at Wide Open Throttle, that is the indicator that you are "lugging" the engine. If this occurs, shift to a lower gear.

No need to worry about the engine in your LA100. I believe we'll all agree, many other other parts on the tractor will wear out before the engine. I've seen many push mowers and tractors where this was the case (various brands).

I will be changing my oil acording to the manual,i have 5 hrs now.Each mowing takes me just under 1 hr.In older days it seemed you could run your mower at a lower RPM but these days its a no no.You might as well get rid of the varable RPM adjust and replace it with a button.

You make a good point Cheez,but i still think with good old TLC the LA100 will give me a decent life (10 yrs maybe more).I have a friend who bought a cheap Rally lawn tractor 10 years ago from i think Kmart and today it is still running very well on all the original parts and no rust.He mows alittle over .5 acre!i do about 1 acre.

mownie, Pressurized systems do not rely on a hydraulic pressurized layer of oil . That is a common misconception. Pressurized systems just get the oil there quickly and consistently. In all cases it is the oil's molecular film itself that lubes.

But what if the splash lubed engine runs synthetic oil & the pressure lubed one uses dino oil? Just thought I'd ask. :-)

I agree that the oil's molecular film is important (crucial even) to provide lubrication. If that weren't true then oil would be useless in a splash lube system. I will disagree with you about the misconception of hydraulic support. Unless the pioneering mechanical engineers were just extremely lucky that their "hunches" worked out. The hydraulic support for the bearing surfaces was the aim of "pressurizing" the lube system. The engines were designed to have very close tolerances to "hold" the layer of pressurized oil. The term "oil clearance" came into use because it was necessary to build these engines to utilize the hydraulic support. The film strength counts for when the engine is idling or at lower RPMs. At higher RPM the hydraulic support comes in as the speed and output volume of the oil pump increases accordingly. Now while you may argue that the bearing surfaces are not hydraulic cylinders, there are still hydrodynamic processes taking place. Engines designed to function as pressure lubed engines suffer great damage when the oil pressure is not high enough to maintain the hydraulic support. That's why lugging an engine damages the bearing surfaces.

The pressure lube system was developed to get continuous amounts of clean cool oil to the bearing surfaces. Without pressure the oil supply to each subsequent bearing surface would not be assured. Pressure measured at the end of the oil gallery assures an adequate supply. Lubrication is for the most part the job of oil film strength. High oil pressure becomes a source of increased friction. Lower viscosity oils are more efficient because they result in lower pressures and flow more quickly to the target surfaces.

There sure are a lot of engine problems reported in this forum, especially considering that the engines are supposedly made to last 1,000 hours.

Hardly a day goes by without a new post by somebody who can't get his tractor engine running, or keep it running, or it has no power.

Somebody said you don't get the benefit of oil pressure in the bearings with splash lube. Well 40 pounds oil pressure is peanuts compared to the strength of something called a hydrodynamic film. When a horizontal shaft is spinning fast enough and oil is touching the under side of it you can place a bearing on top of the shaft and apply unbelievable amounts of
pressure. You can't squeeze the oil out from under the bearing.
The viscous film of oil keeps pulling more oil in under the bearing and supporting all the weight. Splash systems and pressurized systems both work because of this lubrication phenomenon. Oil pumps just deliver oil to the right place.

Anyone who buys a splash lube engine in an LT costing over 1.2K is getting a bad deal in this day and age . It's a technology that is fine in a cheap lawn tractor mowing a flat lawn or a lawn with a few small slopes . But I suppose those mowing 2 acres of heavily sloped lawns on a Murray with a splash lube engine for 20 years will pipe up any time now with testimonies of the virtual indestructiblity of their engines ! And never mind the excessive steering slop in those machines , only 70 bucks or so every 3-5 years for steering gears !

Right ! And there's no such thing as a "fluid bearing". Hovercraft (air cushion vehicles) will not work because there is not a film of oil beneath them. Air hockey is just a figment of someone's imagination. It's impossible to damage a crankshaft and bearings from lugging an engine because the you can't squeeze the oil out from under the bearing because the viscous oil film will just suck more oil out of the crankshaft and oil galley. I give! Uncle! Uncle!

I don't see any reason your LA100 should last less than 15 seasons. If it does not have a filter, I would change the oil every 25 hours or so.

I seem like the little guy here in a mostly non splash and lube crowd.I did research the LA100 before i bought!but i claim ignorance in knowing about splash and lube.For me the LA100 seemed like the right choice for me for my 1 acre,some sloping yard (nothing over 10deg) and i still think it was a good choice.Im one of the few who prefer manual over auto and the LA100 is the only one that is.Thank Cheez and others for your upbeat chat on my type of LT.I tend to baby my machines and the LA100 is in good care.

This thread doesn't give enough attention to the cooling function of the oil. Pressure lube should give better flow, hence better cooling. As far as I can tell from reading, it seems most lube failures are caused by overheating.

In fact, a ZTR I bought last year says to remove the air shroud and clean the grass from the fins every 25 hours. And to change the oil every 2nd time. Also change the oil filter every 4th time the fins are cleaned.

Reading above, I have to wonder what the opinions posted above are based on. I didn't see any comments on engine failures being examined. Perhaps walt or fish could help with some of the engine failures they have seen.

So I will add my experience of over 2,000 hours on a splash lube engine run on hillsides. It has NO filter and the oil only got changed about every 400 hours. It run from 1984 to 1999 when it started smokeing enough that my wife didn't want to drive it anymore. Later, I examined it and found the smoke came from the fuel pump pressure hose from the crankcase to the fuel pump (and dripped onto the muffler). With a new hose and valve adjustment, it runs like new.

This doesn't mean all splash lube engines will do as well.

But it does seem that this B&S opposed twin had very good materials and the mobil 1 that I used also worked well.

The tractor (a gilson) did have many failures.
Belts & blades
mower spindle bearings
Front wheel bearings
Input gear to the tranny
Seat cover ripping
An interlock preventing the starter from running
Gas line cracking

The engine also had failures.
Charge diode
Starter pinion gear
And then the leaking hose
It needed a valve adjustment by now

JerryO

IMO the only time the sling-er will not sling oil is when there is little oil in the engine to sling. I've heard that wives tale about sling-er engines not lubricating on hills. I for one don't believe it, for two reasons. one I seen a cheap Murray mow excessive grades for 10 years. It only failed cause the owner would not check the will let along change it regularly, so it got low enough on oil to over heat it and it stopped. two I mowed a bank at least 60 degrees with a push mower and a rope for several years and that push mower didn't fail.

Even pressure lube engine will fail when there not enough oil in the system to keep the engine cool. So IMO the big question is how long do they run with minimum oil in the engines?????? will the sling-er sling enough oil around to lub? Yes IMO, it's heat build up that kills them IMO. Same goes with pressure lube IMO>

Lots of good information here. I thank all of the posters. JerryO, the tractor I'm replacing is a Gilson YT16. To Mownie and Castoff and Metal, and all the others, thank-you for helping me understand this.

Now, here is what I think. These engines are sold on price. The manufacturers would not be putting pressure lube systems on them if they didn't need them. I think the big driver forcing engine makers to pressure lube is OHVs. It's hard to see how you ensure lube flow to the valve train without it. Also a little keep up with the Joneses. All Honda's are pressure lubed, and the American makers added it to "keep up".

I think my new tractor will be pessure lubed.

Thanks again, steve

FYI, Honda makes plenty of splash-lubed engines as well as pressure lubed ones.

Basing your tractor-buying decision on the type of engine lubrication makes about as much sense as buying a car because it comes with a certain brand of stereo. All this chatter about splash lubrication being yesterdays technology is a speculative. Splash lubing is very much a big part of the engine technology of today because every manufacturer of OPE engines makes them. If splash-lubing didn't work, then everyone would make low HP engines with pumps in them. About all that would accomplish is make such engines more costly to produce and buy.

Go read the archives at this forum or any other forum and see if you can find people complaining about their splash-lubed engines failing. There are MILLIONS upon MILLIONS of self-propelled and push type lawnmowers that have been made with splash-lubed engines and can be found on the dealer's floor right now all over the world. And what about all the water pumps, trash pumps, generators, welders, plate compactors, cement mixers, mortar mixers, log splitters, posthole diggers etc, etc that all have splash-lubed engines in them?

As for pressure-lubing keeping oil temps down, that too is baseless UNLESS.........the engine is spec'd with an external oil cooler. Very few residential grade LT's, YT's or GT's come with such a cooler. Commercial quality engines have them because there is an expectation that the mower will be used almost continuously all day, every day. Very few resi mowers cut grass for more than four hours in a day and often only one day per week.

Without an external oil cooling radiator, the oil inside an engine will reach the same temp as all the surrounding metal components and then stay at that temp, regardless of the method of oiling the components.

There is no question that oil does help keep an engine cool and that is one of the reasons why the oil level should be kept at the mark on the dipstick at all times. The oil transfers heat to the aluminum crankcase and some engines have been equipped with cooling fins on the bottom of the crankcase to help dissipate heat to the air with greater efficiency. Pressurizing the oil has no effect on heat dissipation all by itself.

Honda has managed to find a way to keep their overhead valve train properly lubed with splash lubrication. However, lubing an OHV twin is somewhat more difficult than a single cylinder motor and pressure lubing certainly makes sense.

Whatever happened to the idea of keeping things simple? The old cast iron, long-stroke Kohler K singles with splash lubrication didn't come with the high HP ratings of the engines found in the current crop of tractors. However, when it comes to producing torque that will grunt its way through tall grass, those engines are certainly the equal to any of the latest generation of twins.

And when rebuilding time rolls around, the old Kohler will only need one piston, one set of rings, one connecting rod, one wrist pin and one pair of valves and seats. Anyone want to make a dollar for dollar comparison between the rebuilding costs between a Kohler K 341 and a Command Pro Twin?

B&S V-Twin Vanguard 18Hp (in my 2000 JD GT235) has full pressure lubrication WITH an external oil cooler. Gotta love those Vanguards.

When Uncle Sam sent me to"School" in regard to engines,and lubrication of same,some important facts were presented. Due to the molecural(sp) makeup of water,it is a better lubricant than oil.It does cause corrosion ,rust,etc though.Purposes of oil in engine lubrication is (1)coolng,(2) carring away heat and cleaning,and (3) finally,lubrication.

Mownie is trying to be sarcastic when he said "It's impossible to damage a crankshaft and bearings from lugging an engine because the you can't squeeze the oil out from under the bearing because the viscous oil film will just suck more oil." He missed the part about "if it's spinning
fast enough."

I once made a science fair project that demonstrated the incredible strength of this film. There was
no oil pump pressurizing the bearing. Just oil pulling in more oil.

Lugging an engine means running it too slow for the load placed on the bearing. If the shaft is spinning fast enough to maintain the film strength, the film will support the shaft in its bearing even during the extreme force of the firing stroke.

"When Uncle Sam sent me to"School""

More evidence of senseless waste of mine and other tax payers money.

Walt Conner

Posted by kdiller 6 - PA (My Page) on Mon, Jun 18, 07 at 3:55

B&S V-Twin Vanguard 18Hp (in my 2000 JD GT235) has full pressure lubrication WITH an external oil cooler. Gotta love those Vanguards.
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The Vanguard is an excellent engine but you should be thanking Deere for spec'ing a cooler on that engine. Not all Vanguards come with oil coolers.

Walt, did you serve in the military? If not you might try and understand and respect thoses who did! The Government is full of waste, training the Military is NOT one of them IMO! Course this is just my opinion maybe I'm not like the majority here.

Has to be the longest thread going . I seemed to have missed the point from where Mownie changed from the village idiot to forum genius lol. P.S. To answer the op question , with today's superior synthetic oils NO . Although pressurized oil systems do normally include additional filtered oil , properly maintained splash delivered oil will adequately protect a Lt engine for it,s expected life cycle .