Quality differences between motor oil. brands & bulk oil from oil-change places

You haven't defined what you mean by quality. For example if you think quality means reducing engine wear, there is very little difference that can be measured between brands of oil when it is fresh and clean.

If you had a hundred cars that were all identical and driven identically the same but used different brands of oil. Then if you were also inclined to change oil on these vehicles every 3000 miles, it is extremely unlikely you would ever be be able to determine a correlation between oil brand and engine wear.

If instead you changed the oil every 6000 miles you still probably won't be able to see any differences between most of the brands in wear based on which oil was used. At that maintenance level level you might find one brand where the vehicles using that brand had slightly more wear than the others (after many many miles).

If instead you changed the oil every 12000 miles on your 100 identical vehicles after many miles you would probably be able to see some real differences in the correlation of engine wear to oil brand.

So buy a hundred cars and hire a 100 trained drivers and follow regimen number 3 and in a few years you can come back and tell us what brand provides the best wear protection.

-jim

There is differences between oil brands. But if you change your oil regularly and at a maintained schedule, your car will easily make it to 250K, even if you use a quikie lube with bulk oil. Same with filters. There is a more noticeable difference here between your premium and economy filters. But once again, a regular maintenance schedule will have your car wear out before your engine, even if you use a Fram.

Bulk oil and packaged oil are the same. It is just a heck of a lot cheaper to buy oil in bulk than in the smaller packages.

There are differences between different brands and variants of oil. Largely the additives packages may be different and present at different concentrations. Most of us have a preference for a particular oil, based on personal observations or on advertised qualities. Not very accurate methods, often, for selecting the best product.

All motor oils must pass tests by SAE and a few other agencies. So they meet certain standards. Yet they may be different. Any number of additives can meet performance specs. While most oils can be used in any engine as long as it meets viscosity and service grade requirements, occasionally there is an engine that doesn't like one brand as well as others. This is getting to be much rarer today, however.

If you use Fram filters then you can use any brand of oil because the Frams will filter out pretty much everything anyway.

Petroleum crude oil has both asphaltenic components (large molecules with aromatic ring structures, and other characteristics), branched hydrocarbons both hydrogen unsaturated and saturated, and "paraffins". Paraffins were named this because they were typically very stable and didnt tend to react easily with many other chemicals.

Paraffin waxes are just larger molecules of paraffins. They are so large they are solid, like polyethylene.

The best oil stocks were the virgin paraffinic oils from places such as Pennsylvania oil field. They could be cleaned up by distillation, hydrogenated, etc and made into excellent lubricants (additives were added to even improve on this dramatically).

Alphaltenics can also be beneficiated, but they were not the desired starting materials that the paraffinic oil were.

HTH

Not sure about that. Even a Fram might not work if you buy Mason jar oil. There was a gas station in Chicago that sold oil in Mason jars years ago. Called it re-refined. Looked good. Like honey.

--Vic

It was possible to make a much better oil from re-refining than was normally the result of virgin crude refining, at least in the old days. Some of the sludge forming materials, polymerizable olefins, were largely dropped out in the engines before the re-refining process. With good distillation and reformulation, this product could actually be better than new. And of course with things done poorly, they would just be cheap.

Some brands of oils feel more smooth than others though. Valvoline and Castrol seem to stand out. I prefer Valvoline because it performs better in cold weather.

Damn! A walking Wikipedia! ;)

Didn't we have this discussion already?

I have 6 cars. I better start thinking about 55 gal drums...

Nope, a professional chemist for years.