Jeep Wrangler 4.0 with Mobile Conventional?

[KCJeep]

I have long favored a thick 30 or thinner 40 grade for the 4.0. The only UOA's I've seen on full syn for the 4.0 that impressed me were on Rotella T6, which at your intervals would be a waste. The 4.0 just seems to thrive on an adequately thick conventional.

 

[crazyoildude]

The 4.0 has piston problems also sometimes

 

[KCJeep]

Originally Posted By: crazyoildude
The 4.0 has piston problems also sometimes


Yes it does, in the WJ's and late generation Wranglers the issue is most common in 1999-2001 models from what I have seen, but all years have been affected to some degree. Another reason I like a little thicker oils to cushion those skirts a little bit more. Of course thicker oils would run a little hotter so maybe there is not any benefit. It makes me feel better anyway ha ha.

 

[crazyoildude]

there are also cracked head problems but generally they run a long time. Sometimes we had trouble finding heads for them at a good price.