15/40... 15/50 ?

[yukon25008.1]

Ray from raylar reccomended i use 15/40 oil in the 8.1, I got my cam from him and thats what he/they run in all there 8.1,s from stock to 800+ HP..

i was in walmart today looking around and was in the oil isle.. the rotella which ive used before and is a good oil has 5/40 in full synthetic but there 15/40 is not full synthetic. I looked at mobil 1 whick i run in our tahoe and always liked, They offer a full synthetic 15/50. So im curious how different can they be? Im mean oil pressure is always good and when i was running the 5/30 at temp idiling my oil pressure was down near 10psi and made me nervous at times seeing it that low.. with the 5/40 rotella i have in it now im at 40 psi driving and around 20 at idle.

Please let me know what you guys think.

 

I know amsoil makes a full syn 15/40, im just interested in the mobil1

[dewfpo]

I'm using M10W40 in my 8.1L now. It get's about 6,000 miles to a quart of oil instead of about 3,000 miles/qt with 5W30. I'm a firm believer in 0W or 5W40 engine oils. I've switched everything I own to them. The engines also seem quieter. I drive them in -20F to +100F and these work very well for me.

 

DEWFPO

[yukon25008.1]

So,what,would,be,the,big,difference,bettween,the,two

[dewfpo]

The difference between the 0W and 5W is the thickness of the oil on a cold start (any engine temp less than the thermostat setting). With synthetics they are both pretty close.

 

DEWFPO