Under certain conditions curing can take days. Passed shelf life is a common cause of no/slow cure. If secound coat is applied too soon,surface can "flash"dry preventing solvent evaporation from underneath. Because of this and other issues,I stopped using oil base over 30 years ago unless there were no option. If after venting room,evaporation odors remain strong,I'd alow more time(up to 10 days) if possible. What is the dealer saying?

Edited

Oh my gosh,I posted my reply then noticed you said 3 years. In your case,disregard everything I said.

Oil paint is obsolete technology. Plain 1985 latex was an improvement. The now 25 year old waterborne urethane enamels are far superior to latex. There are other newer single or dual component waterborne pigmented polyurethanes that are far superior to the urethane enamels. And those are like comparing a M4 Carbine to a wooden club to compare to oil paint.