BirdShot

I figure this is also relevant to this thread. Click here for my UOA reports from using 5w-20 in my AP1. 5w-20 was what came in the car when I bought it, then put some miles on it along with autocross.

INDYMAC

That's a good addition to this thread Birdshot. I know that you've discussed the probable SAE grade of the oil in use, but keep in mind that many current 5W-30 formulas seem to shear quite a bit. And it's not out of the realm of possibilities for this to have started as a 5W-30. Last week I saw a UOA posted on Dyson DMW that showed 5W-30 GET fully synthetic sheared to V40C 39.1 and V100C 7.7 after only 1733 miles in a 2011 Elantra (1.77% fuel). The quality of polymers in the viscosity improvers just aren't what they used to be I guess.

BirdShot

It's possible, but in my opinion not likely. Keep in mind I was curious enough to call the service department to find what they would have used and I was told 5w-20, after I retested VIS100 and GC with confirming results. (if I could do it over again I would have thrown in a VIS40 and VIS index)

Your average SAE 30 starts around 10.5 cSt and I'm at 7.1, that's a pretty big stretch even with 1.5% fuel. The GT-1 5w-20 starts at 8.5 cSt, throw in some initial shearing and a slight amount of fuel and it looks about right. I will never know with 100% certainty but I'm pretty confident this was a 20 in the car when I bought it.

INDYMAC

Like I said, based on the homework you've done, I would lean towards 5W-20 grade used in your car.
As a side note, PQIA will be publishing results of bulk oils used by dealerships and auto shops soon. They will be clean samples though...should be interesting regardless.

SpitfireS

Birdshot: do you guys have a test for HTHS?

When the going gets tough the HTHS is the tough one that keeps on going - if you know what I mean

I wonder what the HTHS would be of a fuel diluted sheared down dino 10W-30 that most stil think is the one-and-only oil to ever be used in the S2000 because the manual states so.
And compare it to a well formulated, with quality base oil and additives, 5W-20.
That would be nice.

While you're at it .. test a common 5W-40 too, before and after 5k miles.

It would not surprice me the protection 40 weight users think they are having would dissapear like snow in summer.
And the 20 weight user(s) getting flamed for ruining an engine with that thin stuff are doing way better than everyone thinks.

Thnks2u

My local WalMart is now stocking Mobil 1 0W-40 "European Car Formula" in quarts at around $6.50. This product doesn't seem to have been discussed in the thread.

What are your feelings concerning its use in the S2000.

Cal

INDYMAC

M1 0W-40 seems to shear very quickly to a SAE 30 grade engine oil (V100C). So I would expect it to work very well in the S2000.

zeroptzero

I like the additive package of their 0w40, it seems like a well built oil, I was considering using it at one time. Like Indymac stated it will shear down to a thick 30 weight during it's use which is perfectly fine for this engine, I had that happen with Amsoil 5w40 European Formula too.

BirdShot

Of the massive array of tests we offer, sadly no HSTS. There is really not much demand for it among the used oil crowd

Since viscosity seems to be the #1 topic among the S2k Tribology guys, I will start adding VIS40 and Viscosity Index to my samples. This weekend I will be changing the oil on my 325i track car and I will take a sample. It will be Mobil 1 20w-50 with less than 2000 miles, but 8 months in with autocross and track days.

sillyboybmxer

i see castrol offers a 0w 30 "euro formula"....its not the "edge" which i currently use in 5w 30....
anyone have thoughts on this particular oil?

Edit: just saw Jfusion used this. what did you think?