Because that's what the 4.0 calls for.

 

thats the weight in the manual i got....i guess thats my only reason. I dont know too much about oils, so if there's a reason to go higher/lower, im certainly open to it.

i am



related question: i was surfing around and saw that one of the symptoms of the 0331 problem can be dropping oil pressure. If that is the case, will i see any coolant in the oil that i drain?

Also, when i replace the valve cover gasket im assuming i will be looking down at the cylinder head (im kinda new to engines)...so if there is a crack i might be able to see evidence then?

 

You said you were going to buy Mobil 1. Can't be full synthetic with GRP III base stock ...

 

Mobil is a full, you may just not consider there base stock to be as pure as some others. No matter Mobil 1 is pretty good stuff @ 32.99 with the Mob1 filter.

 

GRP III is not synthetic. Not synthetic=not full.

 

I agree with you that it is not group V synthetic (which is really the only true "full synthetic") In the US of A though group 3 can be labeled as synthetic so to me it will do but I agree you are correct on Mobil1 does not use group V.

 

I would recommend 5w-20 or atleast 5w-30. 5w-30 will be the same @ operating temp but a little better @ startup when compared to a 10w-30.. I like the lower 5w-20 because it will increase flow @ operating temps when compared to 10w-30.

yes, you could see coolant in the oil and yes you could possibly see the crack when you take the cover off.

 

If your oil looks ok and the head checks out try replacing your sending unit