Originally Posted By: wings&wheels
Originally Posted By: CATERHAM
NateDN10 and Hokiefyd are correct.
Originally Posted By: wings&wheels
Does the 2004 S2000 manual also indicate that a synthetic 5w-40 may be used in extreme conditions or similar language? My 2001 did and I believe Honda spec's 5w-40 for the ROW.
I always used Redline 5w-40 in mine, while it may not have made much of a difference it was comforting when I was playing around w/ the 9k redline.w
Yes Honda recommended 5W-40 for cold temperature starting not high temperature protection.
RL 5W-40 with it's HTHSV of 4.6cP is effectively a very heavy 50wt oil, actually heavier than M1 15W-50 at operating temp's and therefore massively heavier than necessary for the S2000 engine. I'd be surprised if the oil pump ever gets out of by-pass mode at high rev's.
A suitable RL oil choice would be their 0W-30.
I would be hesitant to use an 0w-30, but if I did it would be RL's. Given the recommendation of 10w-30 here and 5w-40 for ROW, it appears that someone at Honda felt this engine had higher then typical viscosity needs. This is my somewhat experienced opinion...and we know what most opinions are worth...
My question would be why the ROW (Europe and Japan) recommendation, at least when I had mine from '01-'05, was for 5w-40 if the engine did not benefit from a higher viscosity?
I just did a quick check of the Castrol and Mobil UK websites and they still recommend 5w-40 and 0w-40 respectively. Mobil's tech folks here recommended 0w-40 when I contacted them back in '03 before I did a few HPDE's in California w/ the car. Obviously there is a lot at play in manufacturers' oil requirements: CAFE, anticipated use, etc. but I find it hard to stray too far from the handbook.
To summarize, I'd guess that the F20/22 engines do benefit from the higher viscosity..again, one finance guy's opinion on an engineering topic..
Searching the ROW to see what's recomended doesn't make a lot of sense to me. There is no evidence to suggest CAFE had any influence on the oil recommended for the F20/22. And as has been mentioned the 5W-40 rec' was made for cold starting below -10C.
From the sound of things this newly acquired car is going to be driven normally here in NA. A light 30wt oil (HTHSV 3.0cP-3.2cP) is the preferred viscosity that Honda recommended and I see no reason to deviate from that.
If the OP was going to track the car, I'd suggest first installing a good oil pressure gauge and fine tune his oil viscosity choice based on that.