Hi,

since I can't make up my mind what oil to use next and seeing this[1] poll, I thought we could have one here specific for the 6.2s.

So what oil are you going to use next, and why?


[1]: http://www.dieselplace.com/forum/showthread.php?t=197172

This isn't really a 6.2 specific topic.

In addition, oil choice generally comes down to personal preference (and effective ad campaigns). Many people defend their preferences with reasons, but the untold bottom line in most cases is "I liked the packaging" or "my dad always used it way back when" or "it's cheap."

For the record, choosing an oil is pretty easy. It's not a black art, it's not all about advertising and various claims and "my uncle al has a truck that he ran with such and such an oil for twenty years with no problems" sort of thing. There are standards for these things that are publicized and tell you how good the oil you are buying is.

First you make the obvious reduction... Look at the various oils, determine what is properly rated for use in the engine. Read the ratings on the back of the container. The API ratings are the thing to look at. You'll see a rating such as "SF" "CD" "CH" or something similar, possibly (probably) more than one. The first letter tells you what the oil is rated for. An "S" stands for spark ignition, a "C" stands for compression ignition. The second letter tells you how good of an oil it is... The farther into the alphabet it is the better the oil. Back when the 6.2 was new the oil recommended by GM had to have both SD and CD or better. These days I don't think you can even buy an oil rated that low, many are G, H, or higher. Oil has come a long way. Pretty much anything you can buy is fine (although make sure it is diesel rated). Naturally the better oils are... Well... Better... But you pay more for better and better oils, it is only worth it to a point.

Synthetics? Personal preference... I don't think it makes sense with anything this old, but it's up to you.

This isn't really a 6.2 specific topic.


Not in general, but asking what people use in these engines, it's specific. They will apply the considerations you mention for this engine and eventually their experience with one or the other oil in it.

Like I'm using Delo 400 the last two or three changes, but I'm not very happy with it. It seems to wear out pretty fast --- just my personal impression. So next time, it will probably be SAE 30 for the summer.

But how can you tell your oil is "wearing out"? Can you get a little on your hands and it doesn't feel as slippery anymore? It's virtually impossible to tell. Unless you're going on appearance, and that has very little to do with the oil itself... It's got more to do with contamination (might look into better filters - now there's a topic that would have some interesting discussion). Even if you send your oil out and have it analyzed what they send back won't regard the oil itself, it will tell you what contaminants were in the oil.

It's hard to have a bad experience with any oil... It generally just does its thing. If it isn't good enough your motor cooks... And how often does that happen because of bad oil (not contamination or lack of oil)?

The truth is that oils don't really wear out anymore anyway. They will far outlast your oil change interval (assuming you use a normal interval). The problem is that they get so dirty (especially on these diesels which get a lot of soot in the oil)... Oil development has gotten ahead of filter development a little bit. ;)

I'm using Rotella 30W. That's my other vote :)

personally i use cheap walmart farm diesel oil with the SD/CD rating...buy it in 20 litre pails for 27 bucks...motor hasn't died yet...but now that i work at a shop i'll be using...shudder...mopar 15-40 diesel...if it's good enough for cummins its good enough for me

My vote is for the 15-40 Rotella (non-syn). Probably just because it's what I've always used. Except for that time when I tried the Rotella synthetic in one of my seasoned 6.2's. That stuff seeped out of places I wouldnt have thougt oil could seep out of. Went back to the non synthetic and stayed that way ever since.

I Use Kendall 15w40 Sd

What does WalMart sell? I think it's Delvac. That's what I use...

Didn't someone just have an issue with using synthetic oils here? If I recall, their truck started smoking alot more and the reason was the synthetic oil was so thin, it was able to slip past the piston rings.

I use Rotella 15w40. No reason other than it is inexpensive.

But how can you tell your oil is "wearing out"?

I can tell by how the engine runs. It's different after an oil change with the fresh oil in it and slowly deteriorates from there. 5W40 synthetic in the 6.5 in the Tahoe lasted 5k, 10W40 a bit longer; the 15W40 in the 6.2 in the Suburban lasts about 2--3k.

Call it personal preference if you want to; it's just my feeling/impression.

For filters, I've been using Delco and Purolator on the Tahoe, Delco PF35L on the Suburban, but last time I found that autozone doesn't have the Delco anymore and got a Mobil 1 filter.

The mobil 1 filter has a lid around the inlet holes. That seems to be a vent to prevent the oil from running out of the filter when the engine is not running, in applications where the filter doesn't point downwards. It makes the filter filter hard to fill before installing, and it may act as an obstacle in the oil flow, so I'll try to get another filter next time.

I like using Royal Purple 15W40 full synthetic in my olds 5.7 diesel.My engines seem to run super smooth with that in the crankcase.I even added one of those filter-mag assemblies to the oil filter itself.That combined with RP engine oil should enable a very long lasting engine.

always have always will use delo 400.

Didn't someone just have an issue with using synthetic oils here? If I recall, their truck started smoking alot more and the reason was the synthetic oil was so thin, it was able to slip past the piston rings.

I use Rotella 15w40. No reason other than it is inexpensive.


synthetics aren't good for a worn out engine that already burns a bit of oil...or consequently a worn out oil that soon will burn conventional oil....synthetic oils have smaller molecules and as such will allow easier blowby in a worn engine, however in a NEW engine with proper tolerances set and everything in working order, synthetics have better wear and break down characteristics....the mechanics i've learned from say anything over 120K, use conventional...sythetic will just keep your engine happier until that point, then let the conventional ease your engine through retirement....

Mobil one --- my truck runs quieter, and after two oil changes no more burning.

Winter, European Synthetic 5w40, starts so much easiser and runs smoother, no oil burning or leaks. Summer, good old Rotella 15w40.