Scientific used oil analysis - anyone have a favorite oil based on these?


I am on some car forums where people get used oil analyses in order to maximize their oil change intervals based on the type of oil and driving conditions their car experiences. It sounds like just about any conventional oil will work fine for most vehicles with the 3000 mile change interval and any oil filter while people have gotten much farther with more costly synthetic oils.

Has anyone here really found a standout oil based on these scientific tests? Some of the car forums I am on really suggest any European rated oil of the proper viscosity or slightly thicker. I understand the specs for oil are a lot more stringent in Europe than the USA so they typically have better oils.

It also seems that people like running a slightly thicker oil than specified in the manual, especially in hard use situations like racing. For example, I see references to people using a Rotella T6 5W40 in engines that call for 5W30 or 10W30 without any issues. The wear metals in the analyzed oil are much lower although there is about a 5% penalty in mileage due to the thicker oil. It sounds like the drive for increased mileage by the EPA has led automakers to suggest a thinner oil than might be ideal for engine wear. Now, that being said, if you can get 200,000 miles or more out of an engine using a thinner oil, that 5% fuel economy savings will more than likely more than pay for a new engine or rebuild.

I am currently running synthetic in everything I own. This includes mowers, etc. as well as even my two cycle mix oils. Some of this is the store brand synthetic when it is on sale with whatever brand filter they have bundled with it for my older trucks. My lowly Geo Metro gets the Mobil 1 European spec 0W40 as this is an oil that has been highly recommended by enthusiasts of these tiny little cars and their engines. Although any 5W30 meets the manufacturer requirements, these tiny little engines are hard working and hard on oil. They are not forgiving to having dirt/sludge in their oil pressure regulators, hydraulic lifters and such. A common problem is something causing the hydraulic lifters to overpump and then the valves burn. For the money, you cannot beat the price of this European spec Mobil 1 as it goes on sale for the same price as all the other Mobil 1 products. I understand some of the other Euro spec oils are actually better, but this one doesn’t cost me much more than conventional oil in most cases.

Anyone here big into oil analysis? I have never done it but have always been curious. If so, has anyone found a favorite oil or at least a favorite oil for the car it is being run in?


The thinner oil helps with emissions and fuel economy until the oil is warm. Then when warm it acts as a thicker oil. I always use synthetic now due to my V6 99 Camry had know oil sludging problems. I now use it in all my vehicles. I change it at 5k miles. I have not done any oil analysis. We do it to our hydraulic fluid at work. I personally would not pay to have the analysis done.


I could never be bothered sending oil for analysis. I’ve never known anyone to wear out an engine with reasonably regular oil/filter changes. My brother used whatever dino oil was on sale, sometimes Pep Boys store brand, and whatever oil filter was cheap, and he sold his car with 285,000 miles on it. Geo Metro engine is a good, mechanically strong engine, but I certainly would not call it hard-working. Same deal with a Metro that my BIL had. He used whatever dino oil and oil filter was on sale and changed it every 4,000 miles. The engine was still like new when the car failed inspection because the sub frame was rusted away. I see the point in being diligent about regular (4,000-5,000 miles) oil changes, but I’ve never seen an engine wear out on dino oil.


I remember when they had some oil sludge problems with Toyota engines. This is definitely a good candidate for synthetic oil.

As for the multiple viscosity oils which almost ALL modern calls call for, I understand they behave as follows. If you are running a 0W40 and you start your engine cold… The oil will behave as a 0W straight weight oil would behave at a that specified cold temp. I forget of this is 32 F or what, but there is a temp spec for it. Once warm, the oil will behave as a straight 40W would at a specified temp. I forget this temp but it might be 100 F. All oils thin out as they get warm so it isn’t like a 0W oil turning into a 40W oil as it gets hot. It is like a 0W oil not thinning out as much as you would expect as it warms up so it behaves like a hot 40W oil when warmed up.

I was thinking the same about the analysis. It looks like it costs about $20-25 to have done. This wouldn’t pay for itself if done every oil change but could see it getting a more economical interval established so you aren’t changing fluids that don’t really need to be changed yet.


Yeah, the Metro has an issue with the front subframe or “frame horns” rusting away. I sprayed some high-dollar internal frame treatment inside mine after blowing them out with a high pressure washer and letting them dry out to prevent this on my car.

My Metro came to me with an engine that had been neglected and was in bad shape because of poor owner maintenance. I began shopping around for a good used engine and located one that appeared to be in good shape in a junker car. The front passenger side was up on blocks because the front subframe and control arm had fallen off as the car was being driven down the road. The CV axle had been busted in half during the episode but the engine appears to have lived a clean life with adequate oil changes. I was able to swap this tiny engine by hand without a hoist and the new one has been serving me very nicely.

With this car, I figure I might as well treat it as well as I can. Sure, it was a cheap car from the start but where else do you find something that routinely gets 50+ mpg without the price tag of a hybrid? You can spend a little extra money on oil to keep something like that going so this car gets the same oil that BMW and Mercedes spec. The Metro forum guys all swear by these oils for keeping these small engines healthy. Stuck rings and burned valves are common when oil is neglected.


I haven’t gone by the analysis (though I’ve had them done), but my current vehicle uses some oil with Mobil-1 in the sump. Less with Valvoline Synpower, and apparently not a drop with Amsoil on board. I noticed that both Mobil-1 and Valvoline seemed to thicken or degrade near the end of the oil change interval–the cold oil pressure was higher, as was the peak pressure when warm. Amsoil doesn’t seem to change much.

So I’ve been kind of a convert to Amsoil. I change oil 2-3 times a year, usually at 5-6K miles, though I will change my oil in the spring regardless of how little miles are on it after enduring a winter of cold starts and rich mixture while warming up. Between Amsoil being good and that I can usually get it on sale here for around $6/qt. (for “OEM”), it makes it an easy choice for me.


I thought a lot of the Toyota sludge was due to owners not changing their oil frequently enough.

I understand that Toyota did accept blame, but I firmly believe that if the oil had been changed every 5000 miles or 6 months, whichever comes first, at least 90% of the sludge problems would not have occurred in the first place.

There seems to be a misperception that oil is changed only on a mileage basis. I don’t know how this got started. Anyways, with the short distance driving that many of us subject our cars to, by the time we hit those 5000 miles . . .


I have read that many of the Mobil 1 products such as 5W30 and 10W30 are mostly comprised of Group 3 base oils which are simply very highly refined conventional oil products. I understand that these oils wouldn’t meet the criteria for being a full synthetic in Europe, hence the reason I like the Mobil 1 European spec stuff. I have also been told that the Mobil 1 0W30 has a higher percentage of Group 4 base oils. I guess several people have sent various samples of virgin oil in for analysis and the labs have provided this information. I once read the FAQs on the Mobil 1 site and someone asked about the percentage of various oils in their oil. The response was something to the effect that this was a corporate trade secret or proprietary industrial information. This kind of response kinda makes you wonder about how good their oils actually are. I am sure Group 3 oils are still quite good for most applications.

I have heard that some engines will burn certain oils but not others. Most of this is actually not past the rings but due to the oil vaporizing and being burned through the PCV. I have also read about the viscosity breaking down on some oils sooner than others. I always understood that most oils tend to thin with use as the molecules become sheared but have also heard the opposite as your evidence indicates.

Another thing I seem to notice after changing oil is that the lifters and such always sound quieter. I don’t care if the oil has 3k or 6k, but I always seem to notice this.

I have read enough about the Rotella T6 5W40 as to not question its use in small air-cooled engines where the oil undergoes a lot of thermal and shear stress. Since the tolerances in an air-cooled engine are not nearly as tight, I don’t worry about the thicker oil causing in problems. I am not so certain that this is the best idea in some modern vehicles with much tighter tolerances in the bearings and such. Also, many aspects of the valve train rely on oil of the proper weight to operate properly. This includes lifters, cam phasers, and other methods of variable valve timing. While thicker oil might not harm crankshaft or main bearings, it might cause all sorts of problems in the top end in certain engines.


I agree about the Toyota sludge problems. While Toyota should accept blame if the manual stated to change the oil at too infrequent of an interval, I don’t think the engines were inherently defective. I know people who had cars subject to this issue who either ran some type of full synthetic or mainly drove long distances (highway miles) and never had one bit of an issue with oil sludge. You can open the oil cap and everything is clean. I also know people who just changed it at every 3000 miles because that is what they always did and their engines were fine too.

On the other hand, I know several people who had cars with the Chrysler 2.7L engine. It seemed to have problems no matter how it was driven or the quality of oil used. That engine seemed to be a real piece of junk and nothing could keep it from having problems. One of my friends made it past 100k when the engine threw a rod. The tow truck driver told him this was very common with these cars and asked him how many miles. My friend had always used synthetic and the driver was shocked to hear he had broken 100k with this engine. Of course being a tow truck driver, you aren’t going to see the ones that last!

I understand that some of these European or import spec oils came about because of sludge problems early on, especially the advent of turbocharging which will put exceptional stress on oils.


IMHO any oil that meets SAE and API standards is as good as the next. Because an oil can be proven in a lab to be superior in one category or another does not mean that it’ll enable your engine to last any longer. The trick to long lasting engines is to buy a vehicle with a reputation for quality and change the oil & filter often. And to use the correct spec per the manufacturer’s recommendations.

I thought a lot of the Toyota sludge was due to owners not changing their oil frequently enough.

It was actually due to Toyota raising the internal temp of the heads in the engine by drastically decreasing the size of the water inlets. This was for better emissions.

The problem didn’t show up IF you changed your oil regularly (every 3k miles)…or if you use synthetic. The problem only lasted 3 years…then Toyota redesigned the engines again.

As for oil analysis…Never bothered with it. It seems like a big waste of money to me. I hear people do it get the maximum use out of their oil. The problem with that is you have to keep doing the analysis because engine parameters change over time and use. You can’t get a reading that says you’re good for every 10k miles…and expect the same when the engine has 50k miles on it.

Just change the oil per manufacturers recommendations…and you’d be fine.


Check your owner’s manual for specific requirements beyound API certification and use the recomended oil change intervals. Use any oil that meets these specifications. Any earlier changes intervals or higher priced oils will have a greater effect on your pocket book and sense of well being then the longevity of your car . Use the money you save in expensive oils and oil change intervals to doing things that would add life to the cars body which is the single most expensive component and the most important for a car’s value.


If you use an oil that’s approved for your engine you will not notice any difference in the analysis when oil is changed at the proper intervals. I’ve used dino and semisynthetic, and the analysis always showed 50-60 parts per million wear metals and no significant viscosity change. The condemming level for wear particles is 200 parts per million, and I never reached that.

Trucking companies use oil analysis as a condition monitoring tool to detect anything going wrong with the engine. They also use it to optimize the oil change interval, like irlandes did.

racing engines now use a lot of full synthetic 0W20 to get maximum power. It causes more wear, but races are seldom longer than 500 miles.


One of the problems with multigrade dino oils in air cooled engines is that they suffer viscosity breakdown in high temps and air cooled engines run much hotter than water cooled ones in the summer. I would suspect that synthetics would be stable longer but don’t know it for a fact.
I use 5W30 in my snowblower (1972 8hp Airens) and straight 30 weight for my 1978 Cub Cadet mower. My car requires synthetic.


Yes, synthetics hold up to the heat better than dino oils in an air-cooled engine. I understand the dino oils marketed just for small engines do contain a greater degree of anti-wear additives and are better suited for use in such engines. These anti-wear additives are not good in engines with emissions control systems such as O2 sensors and catalytic converters. One that comes to mind is ZDDP, a zinc compound.

I sometimes run my riding mower through some pretty thick grass and it starts struggling, especially if I am due to sharpen the blades. It used to start blowing smoke pretty good during any sustained runs through tough cutting grasses. I suspect the engine and oil was getting hot and either thinning out so much as to bypass the rings or just start breaking down and burning due to the heat. This hasn’t happened since my switch to the Rotella T6 5W40 full synthetic. The best part is this stuff is like $22 for 5 quarts at Wal-Mart. I would probably run this in your equipment if it were mine but this is just my opinion.

As for the oil analyses I have seen, some are being done in cars that are being turboed with high boost pressures, raced, or otherwise pushed well beyond their intended uses. It seems that some oils really do stand out in these situations. Oils meeting the manufacturer specs no longer hold up under these extreme conditions and turn to sludge and/or result in excess wear particles. The Rotella T6 seems to hold up quite well in these situations.

As you say, the most important thing is to keep the body from rusting. I know of plenty of perfectly good engines that have been junked because the car they are in turned to rust. I happened to get ahold of one of these to replace one in one of my cars.


I don’t want to start anything but I just use Mobil dino and syn depending on what the book says for the weight. I just change dino at 3000 and syn at 5000 and don’t worry what anyone else says. I can change oil for the same cost as an analysis so really don’t see much benefit for non-fleet type operators. I’m really looking forward to my 30K transmission change too-not.


I drive a truck powered by an engine (300 I6) dreamed up in the doo-wap era. Any oil on the market is so much better (excepting ZDDP) than what it was designed for that “whatever’s cheapest” is more than good enough. It’s like saying, Manning is a better QB than Tebow…but either one’s more than sufficient to play catch with my kid.

I do tend towards diesel oils and/or a splash of ZDDP supplementation in deference to my flat tappets.

As to EU oils being “better”: well, they’re different. They have more additives (antacids, detergents and dispersents) to compensate for the crazy OCIs that, IMO, were forced upon motorists in furtherance of a claimed eco benefit.

The downside is there’s a lot more “other than slippery stuff” in it to artificially extend its useful life. As a parallel, you could “add stuff” to ground beef to let it keep in the fridge for a month: is it “better”?

As for the “environmental benefits” of not changing oil, realize that all those arguments hinge upon a “statistically average” % of the used oil being improperly disposed of. Practice good oil hygeine, and 99+% of that argument is irrelevant to you. (As for me, a local business pays $1/gal for the stuff, so I’d have to hate money AND the environment to illegally dump mine!)

use 5W30 in my snowblower (1972 8hp Airens) and straight 30 weight for my 1978 Cub Cadet mower.

I think running synthetic in a snowblower or lawnmower is a no brainer. The cost is insignificant since most of us change the oil just once a year. In my snow-blower and mower I use 5W-30 synthetic.



I once requested a used oil analysis kit, but I never got around to using it or sending it in.

It looks like you’re not going to get direct answers to your direct question, but as a regular of this forum, I’m sure you expected that.


Yeah, I pretty much expected many answers. Something else I do understand about the European spec oils is that besides the additional additives, the base oils are also better and better able to withstand thermal breakdown and shearing over time. I also understand that the additives are less likely to foul emissions system components for any oil that does get passed through the engine and burned. Either way, I understand that many oils contain a high percentage of “stuff other than the slippery stuff” in additives. I seem to remember the early days of 10W40 and such having issues with too many additives and too little oil or the additives breaking down WAY too fast because extra additives were required for such wide viscosity ranges. Obviously the base oils and their additives have improved as we are now running 5W40 and 0W40.

As for small engine equipment, I see synthetic as a definite bonus. As with everything else, the deck or whatever else on the equipment is likely to rust out before the engine dies but at least one shouldn’t have to worry about breathing smoke from a neglected oil burning engine. I have had used mowers like this and do not like smelling like an oil refinery after finishing the yard.