i found out a while back that the company i work for uses 15w40 mobil delvac in all there worktrucks,which are chevy 1500 silvys with 4.3's.because they buy it in bulk and get it cheaper,than say,5w30. mostly. what are the effects of using this heavier weight oil in a gas engine? long term?

 

My Dads 96 Surburban has 299,000 on it and has only had Rotella 15 40 in it since new.

So i dont see a problem with it.

But its just a workhorse/daily driver,.

IMO 5w30 is fine and starts easier in cold weather and frees up power vs. a heavier oil.

 

u think putting 5 quarts of 5w30 and 1 quart of lucas, is the equivilent to using all 6 quarts of 15w40 in an oil change?

 

In all fairness, the older style blocks could have thicker oil. The LSX blocks are much more precisely engineered and really should be running a 5w.
Can you imagine how thick a 15/40 will be when it's cold?

 

What about a 0w40 like the Mobile1 Euro blend. I run it in all my crap and it seems to work real well. Provides great startability and cold engine flow yet does not thin out as much as a 5w30. Mercedes Mclaren SLR along with BMW's new M3's run a 0w60

 

stock ls motors a thinner oil should be ran but modded motors all run different clearances from different builders and are often larger than factory so a thicker oil should be ran . i know i wouldnt put 5w in my new 7.0 lsx. i am going to run a 10w-40 non synthetic and just keep the oil changes more frequent.

 

Exactly

 

Personaly I run the thinist oil I can get away with regardless of cost. The thick oil likely wont hurt anything, other than rob some power, and mpg. A thicker oil also takes longer to get circulating. Unless the engine is set up with clearences requiring thicker oil I would stick with 5 or 10w-30.

 

15w-40 will kill it!!!!!


although that's what I'm running it in my truck, doh! (see sig below)

 

I agree with ya,only i run what ever the Owners manual calls for which seems to be 5w-30 mostly...

I believe the trick to keeping the motor healthy is to change the oil every 3500,thats what i do and i notice the oil still has a caramel color to it which is good! if you change your oil and the oil is black you need to change it sooner!

Unless your driving a Diesel ! Diesels i change every 5000 ... Due to the EGR's Diesel oil will be black with one trip around the corner... But they Hold from 12 GM to 15 Ford, Quarts so its a little different....

If you love your Truck like i do then Run the required oil and change it every 3500 thats the best ya can do for it,any sooner is a waste of good oil...