From what I read on Amsoil's site they are better in many ways than M1 and slightly cheaper. What I dont get is Amsoil and RP never compare against each other. So which is better? Amsoil is supposed to be good for 30k miles, what about RP? I want to be sure I am using the best oil for long life of my abused engine.

So, openions welcome and any true knoledge about these oils is highly appreciated.

Which is best?????????????????????????

 

You know we had a poll on this same topic a while back... it had quite a few pages too. You may search that for further info, or go over to tech and perform the same search... their poll had like a million votes.

 

as far as synthetics go I prefer motul or redline as they are made from Group IV oils, some amsoil products are as well.

otherwise Rotella Synthetic is made from Group III oils, is as good as any "so-called" synthetic oil and is cheap, besides, most synthetics these days are made from Group III oils anyway (you can thank Castrol for that), so just get what's on sale.

some info:
Group III oils have properties approaching or equaling synthetics, so long as the temperature is above about 40�. Group III based oils are often claimed to not perform as well as synthetics in a couple ways: their low temperature performance is not nearly as good, it is sometimes claimed on the basis of the "ball bearing test" that they offer lower impact resistance, and since their flash point is slightly lower it is claimed that they burn off more easily. However, most modern engines are water-cooled, so it's hard to see how the slightly better flash points of the synthetics ever come into play. The low temperature performance of the Group III oils can be improved enormously by blending in a relatively small amount of synthetic base stock and other additives.

Group IV oils, one process for making synthetic base oils is to start with a chemical called an olefin, and make new molecules by attaching them to each other in long chains, hence "poly." The primary advantage of Poly-Alpha-Olefin "PAO" base oil is that all the molecules in the base oil are pretty much identical, so it's easy to get the base oil to behave exactly as you like. PAOs are called Group IV base oils.

 

the castol 0w30 is suppose to be good stuff too. thats what i have in there now with about 4,000 miles on it and it looks nice and clean. about to change it just because i'm over 4,000 mile. i found the part number to the long oil filter made by purelator or however its spelled. when you go to buy a filter get one for a 99 2500 they are the long ones.

 

I run M1 but seriously think if you ran any "Quality" lubricant and changed it religiously that there's not much advantage. (?)

 

knowing ron he is looking to go the distance with his oil. so he is looking for a oil that will last a long time between changes.

 

My Thoughts exactly....

 

hell i just use good 'ole castrol 10w30 ALL the time

 

Hate to be dense, but are you saying that the oil filter for a '99 2500 wil fit my '05 2500 (w/ the 6.0l)???

This engine has a very small filter on it and I've been wanting a larger filter since I tend to go 5k miles between oil changes. I'm running M1 5w-30. Thanks.
-TK

 

yes any 4.8/5.3/6.0L filter will interchange on the trucks