Here are the first UOA reports from my S2000’s engine oil and diff.

A quick summary: I bought this car over the summer with STR autocross in mind. This 2003 AP1 has 46,000 miles and has some records of maintenance including mostly engine oil changes. No record of a diff fluid change. The engine oil has roughly 2000 miles/5 months and the diff I believe was still the factory fill. Within the last 2000 miles I have about 50 autocross runs and this engine sees all 9k. I forgot to sample the transmission when I drained it but I do have a record that is has been changed at least once.

Even though this engine oil had only 2000 miles, I figured the 50 autox runs would be enough to show what kind of wear this engine is seeing. I was a bit surprised to see very low wear metal content. Traces of Fe, and Al suggesting extremely low cylinder region wear. As for bearings, a small amount of Cu, but zero Pb, Sn or Ni (is there another source of Copper in the F20/F22?). A noteworthy metal is the Ti at 101ppm. An increasingly popular anti-wear additive is a liquid titanium element, Kendall has used it for years and you may have seen Castrol Edge is now using it as well. Other additives are all pretty standard per this oil and no evidence of coolant or dirt contamination are present. I retested the metals and they confirmed.

A small amount of fuel dilution that has probably thinned the Viscosity slightly, I am at the bottom end of what the SAE 20 starts at but still within spec. TBN and Oxidation/Nitration show this oil had tons of life left in it. I used Amsoil SSO 10w-30 for the new oil change but I will switch eventually to a 5w-30 or even 0w-30 in the future.

The Diff results were not so nice, pretty nasty actually. Like I say, I had no record of the fluid ever being changed so this has likely been in the car since it was new and if that’s the case this oil would still contain break-in wear. The ICP revealed excessive amounts of gear metal; Fe, Cr, Mn, and an unusually high amount of Ni. After seeing this, I had a slide made for an Analytical Ferrography report (microscope). My co-worker is one of the best in the world at this and made the Ferro report for me. The view from the slide actually put my mind at ease. The majority of the wear particles are ultra small, with only a small amount of larger particles. This revealed that the majority of the wear was actually corrosive wear at a molecular level along with rubbing wear from simply being over-extended.




When I changed the fluid the magnet was full. I did use new fluid to flush thru the diff while the drain plug was out. I filled it with Amsoil Severe gear 75w-110 and I will probably drain it again in 6 months or so to see what it looks like.

 

The results look great. So the oil started as a 5w20 ?. No lead wear is extremely impressive given the use of the vehicle, even for a short run. There are other sources of copper in the engine such as the oil cooler, I think the thrust washers are a copper source too. Either way 3ppm copper is very low.

Given the age of the diff fluid and the possibility that the fluid in there may have been the factory fill the wear numbers look good if you consider them on a ppm/1000 mile basis, and account for increased wear during break-in still being in that small sump. That fluid must have looked nasty when it came out. I can't believe someone (previous owner) would leave diff fluid in this vehicle for that long, damn.

Looks like you got a good vehicle there, I like the reporting of that lab, and that is cool to have a friend that can give you extra advice on the results. Thanks for posting the info.

 

any pic of the drain plug contamination? A few of us have posted pics, myself included which may give you some insight.

 

Who is a good online source for order a UOA kit? Thanks!

 

Funny enough, I actually had no idea the engine oil brand, type or grade before I tested it. The car came from a dealer and they change oil on all incoming used cars. All I knew was that the oil was changed at x miles. The titanium was a dead giveaway because only a few companies use it. Along with that, the other additives were consistent with Kendall GT-1. I re-tested both viscosity and fuel dilution and they confirmed each time so I was pretty confident this was an SAE 20. I added the oil description to the report with 90% certainty.

After this I called the dealers service department to try and find out what they use. Sure enough, the standard oil they buy in bulk is Kendall GT-1 5w-20.

 

Thanks for these great posts BirdShot! I predict that you will be an MVP on this board with the resourses you have at hand, and your real world data base knowledge. Your testing equipment is top notch too.

I look forward to many more posts from you, and hope that you can include clean sample results as well as UOA's.

Also, are TAN and V40C tests available?

 

Thanks! Like I have said before, I have been impressed with the tribology knowledge on this site. It's nice to share results with others who know what it all means.

I do have Vis 40 and TAN, but I don't typically add them to my engines, I may start. The diff had TAN in the test package but it was the only test that had not been completed and I wanted the reports for the weekend. The only "additional" test that I added was Particle Quantifier. For this first time the number is arbitrary, but in future samples it will be a good cross reference with ICP metals.

 

I know a 20 weight won't hurt this engine in most circumstances, we've seen it on at least one other UOA and now this one, but I can't believe a Honda dealer would put in bulk 20 weight oil into an S2000. It's just not right to do that to a customer IMO. I'm always skeptical of bulk oils, at least the Kendall product is well built. Great info.

 

your right and I agree, but I should specify that this is a Mitsubishi dealer. Mostly new cars on the lot with select used cars. If anything, I am at fault for trusting them this long to have put the correct oil in. But as you say the SAE 20 seems to work just as well.

My opinion is that the Honda SAE 30 is the best middle ground weight, but you will not notice much difference, nor will it be detrimental to your engine using a SAE 20 or 40. Just my opinion.

 

Great UOA for a car that sees spirited driving. This is more proof that an XW-20 oil works well in this engine. I'm not surprised.

That's a really interesting analysis of your diff. I've never seen ferrography images like that before. Where were these taken? I'd like to understand what they're all about.

Thanks for posting.