Mine doesn't say anything under the hood besides refer to manual ha but I'm pretty sure my manual says 10w30...and when i went to o'reilly's they said 10w-30 also. I knew guys were using something different so I haven't bought anything yet. I haven't owned the truck long but I changed the oil once and used 5w-30 but I wanted to make sure I wouldn't be screwing something up.

 

Jake,
No worries, I have used nothing but 5-30 since I bought my truck new. Changed the oil today, old oil is a little dark but clean. I change mine every 6000 miles . Have had no engine problems and I buzz mine up fairly often. Good luck...

 

Red-

Does yours say to use something besides 5-30?
thanks

 

No, my cap says see the manual.

 

does your manual say 5-30? im just gonna have to look at mine again. I swaer it says 10-30

 

Just looked at the 03 manual oil chart. The following is from the manual.
The chart says if the temperature raises above 100F use 10-30w. If the temperature is below -20F than use 5-30w. So the actual over lap is -20F to 100F where either oil can be used.


temperature range and variation (Fig. 2).

 

thanks a lot. I feel a lot better going with 5-30 now.

 

This is just me thinking out loud, but I like the thinner multigrade because when the engine is first started the thinner oil gets the bearing a little quicker providing better protection. Oil is the only cooling factor for the bearings and I think the thinner oils generally do a better job of disapating the heat. There is a lot of arguing about it, but that is where I stand. A race motor is another story, but we are driving street engines..

 

Ill throw in my 2 cents: Ive been running Shell rotella T-6 synthetic 5-40 since my truck was new in april of 05. This was after a discussion with my now retired mechanic who knows how hard my trucks are used. In his opinion, the heavier oil serves as a slightly thicker cushion for all of the internals as I over work this truck a lot. 152,000 and no problems on my 4.7 to speak of. 4,000 mi. change intervals and pure one filters. Just changed the coolant for the first time, even though it still tested perfect. Has anyone needed to change their belt or hoses yet? Mine are still original.

 

I used the same mind set for many years, developed it when there was no multigrade oils. Here are some thoughts. Liquids do not compress. Street engines are engineered to have specific clearances, the oil's job is to suspend the rotating components and while keeping them seperated remove frictional heat. The thinner oils can flow through the engine oil passages easier (quicker) than heavier oil. Which means that with the oil pressure remaining constant, the thinner oil has a greater flow which increases it's capacity to remove more heat. In extreme conditions, like cold, thick or dirty oil I think the oil often has enough internal resistance to flow that the volume to the bearings is reduced increasing bearing temperatures. So my way of thinking is that as long as the proper oil pressure is being maintain under all conditions the thinner the oil the better. Besides, heat is loss horsepower due to friction. And we are all looking for more HP. My 2 cents worth....