Oil Viscosity

shotgunner · 11-06-2009, 12:07 PM

Got an '09 Liberty, 3.7 liter and the oil fill cap reads 5W-20 recommended. Had an 07 Jeep GC with the same engine and it had 5W-30 recommended. What gives? Is this all related to CAFE rules or what.
Don't think they changed anything in the engine to require 5W-20. Does anyone have any comments on this? I want to use M1 0W-30 AFE for year 'round oil fill.
Comments would be welcome.

**Elt31987** · 11-06-2009, 12:35 PM

I run Mobile 1 5W-20 and Mobile 1 Filter. They probably run 5W-20 because i think its thinner leading to a little bit better fuel economy which we all know we lack.

**autoboy454** · 11-06-2009, 01:45 PM

most vehicles these days are leaning towards 5W-20 for the fuel economy. Personally I would think that running 5W-30 in the "new" 3.7l's wouldn't hurt anything, as not much had to have changed engine-wise between the years IMO.

DaveJKJ · 11-06-2009, 03:28 PM

Quote:

Originally Posted by shotgunner

Got an '09 Liberty, 3.7 liter and the oil fill cap reads 5W-20 recommended. Had an 07 Jeep GC with the same engine and it had 5W-30 recommended. What gives? Is this all related to CAFE rules or what. Don't think they changed anything in the engine to require 5W-20. Does anyone have any comments on this? I want to use M1 0W-30 AFE for year 'round oil fill.
Comments would be welcome.

I believe it is all related to CAFE. But that is my opinion so I could be wrong. I don't think they did anything to the engine so they could use the thinner oil viscosity. In fact I will bet your owners manual for your 09 says you can also use 5w30. (I believe my 05 3.7 says 5w30 preferred and 10w30 also ok without looking it up)

I am not sure about the 0w30.

Personally, I have been using 5w30 weight synthetic.

RageOfFury · 11-06-2009, 05:34 PM

Would M1 0W-40 be ok to use?

Reason I am asking is because I can get a great deal on M1 European spec'ed 0W-40.

scottunangst · 11-07-2009, 05:30 AM

Quote:

Originally Posted by RageOfFury

Would M1 0W-40 be ok to use?

Reason I am asking is because I can get a great deal on M1 European spec'ed 0W-40.

where's the great deal on 0w-40 that's what my crd uses. be careful running heavier oil in modern engines. back in the '70's we all ran 20-50 in our hotrods. a friend put 20-50 in his late '80's 3.9 dodge van and the lifters starved for oil because the thick oil could not be pumped thru the small oil gallies in the modern engine.