I'd like to see a service bulletin or some actual official document or memo from Honda corporate that directs Honda dealerships to use a weight of oil that deviates from 30 wt.
Besides, if 30 wt was the ideal weight of choice for the track why would Honda communicate anything other than "use 30 wt in all conditions above 0 deg F" which is exactly what it does say?
"Tracking" just means you have arrived at a race track. It is not particularly substantive. "30 weight" likewise can have broad meaning. Yet you seem to take to a very rigid interpretation when reading, like a bible thumper that worships the speed god. :biggrin:
Let's try this another way. So by your logic, Porsche should have specified the same oil weight in their GT3 cup car owners manual, as for their GT3 road car owner manual? Correct? After-all, the road car and the race car have the same engine for all relevant purposes. Think: all those motor-sports shops must be real idiots using the mnfg. specified heavier weight Lucas 20W50 or M1 15W50, instead of going by the factory service guide recommendation for the street car. Makes you wonder about the service schedule too. Shit, what are all those motor-sports shops thinking changing the oil at an interval of every 10 hours, when they could just be doing it at 12,000+ miles like the factory service manual for the road car specifies. What a waste of money. Ignorant Morons.
Here is what you clearly don't understand:
The service intervals, temps & severe stresses experienced in tracking/racing are entirely incomparable to doddling around town. Does it say anything about tracking/racing in the Acura instruction manual that came with your road NSX? NO. However, if Acura had offered a factory NSX spec cup car, I feel confident that the owners manual would not call for the same weight oil nor service schedule.
Let me be clear on this point:
- Dealerships service road cars.
- Motor-sports shops service race cars
Daily driving from work to the dry cleaner - Well covered by the factory manual. Tracking, Racing, Cold-starts in the Arctic circle, Amphibious Conversions, Top Gear launching the car into orbit or crossing the Sahara Desert, Randy Pobst behind the wheel etc - Not so well covered by the factory manual.
Get it? Should be pretty obvious.
Just understand that your proposed practice of putting 40 wt oil in your NSX motor is based on nothing more than a personal theory in an area which you and I have no background in that's been generalized to fit the specific application. I find it hard to believe that someone as intelligent and informed as you would be willing to follow some practice that was supported by no data or expert opinion, wasn't actually recommended by anyone official or knowledgeable about oil or the NSX itself; a practice that directly contradicts the manufacturer's recommendation and has been specifically mentioned by at least the head engineer of Mobil 1 as a practice not to be followed!
The bottom line is do what you want to do to your engine, Ski, but there's never been anyone reputable that recommends anything other than 30 wt in any NSX motor with stock internals in any situation or environment that I have ever seen, read or heard about. And please, I'm not talking about Ken Sax--I'm talking about NSX motor builders. Why don't you ask Basch, Nick Eustace, Jon Martin, Shane or Chris if they recommend anything other than 30wt in any situation including the track?
To each's own, but to be perfectly candid I am really not in anyway interested in what any of the NSX Street tuners or an M1 rep said at a club talk about oil for the track. I really couldn't even begin to imagine caring any less.
If you want to talk about motorsport credentials on a race track... then the Greg Fordahl's, Lee Stohr's, and Arnie Loynings of the world were putting winning race cars on grid at Le Mans and taking National Championships before most of those guys were even born.
Look. If I have a question about a Taitec exhaust or need to replace my cabin air-filter, then believe me, I know who to call.
Well, I've never heard any NSX engine tech or any other expert ever suggest anything other than 30wt for the NSX engine so I don't believe any NSX engine condition exceeds the ability of 30wt to protect it and 40wt clearly isn't the best for normal situations so I really would be reluctant to say anything other than 30wt was the best viscosity for the NSX engine under any circumstances.
I think the practice of using higher viscosity in the NSX engine in any capacity is pure conjecture and assumption and isn't based on any data, fact or expert opinion and the practice is at best less effective than 30 wt and at worst harmful for the $15,000 engine. Your statement about having an oil cooler is the same conjecture, speculation and theorizing that surrounds the practice. Did an NSX engine expert or oil engineer tell you that an oil cooler has an impact on whether 30wt or 40wt oil is more or less effective in the NSX under certain conditions or is it your opinion the NSX heats the oil to a higher temperature on the track than can be adequately handled by a 30 wt oil?
I think Honda is aware that oil tends to decrease in viscosity when hot and yet they still recommend 30wt and so does every NSX engine tuner, not to mention oil engineers have urged people specifically not put a higher than recommended weight of oil in at any time.
What I do know is that if it were beneficial to use anything other than 30wt someone that works on engines for NSXs that are tracked frequently would have said so and to my knowledge they have not.
Unless you have a background in lubrication engineering and/or fluid dynamics I am perplexed as to why you would be sure that 40wt oil in an NSX engine would protect better than 30 wt. Maybe the 40wt's viscosity does decrease when hotter such as at the track but there may be many other technical factors that you're not considering that make 30wt the best choice even in those scenarios. I don't know enough about the NSX engine and/or motor oil to know if that's the case but neither do you.
I am really shocked that some people here would be so willing to ignore Honda and oil engineers and believe that something is going to be beneficial to their expensive NSX motor when not only has any expert never suggested doing so nor have indicated that it was beneficial in any way but have actually denounced the practice!
The suggestion of using anything other than 30wt oil for the stock NSX engine in any circumstance is absolute speculation and is extremely irresponsible. No expert has ever recommended this and it has been suggested by experts that it could damage your engine.
My honest opinion here is that I think you should continue to do what you think is best: go by the factory manual or with whomever the popular tuners are that you trust. The truth be told, for what-ever you are doing the factory 30W oil might be just fine.
Regardless, I think you have said in so many ways that the crew chief for team NSXGMS HPDE racing has made up his mind, and at this point no one short of Soichiro Honda will likely change it. Clearly, everyone should be using the 10W30 spec with the factory oil filters and crush waters without exception before you have an aneurysm.
Personally, I want to know whether I should be putting 40wt in my NSX at the track. Surely we all want to use the best products in our cars at all times and we don't want to use inferior products. If 40wt protects my engine better than 30wt on the track I'd like to know since some here are making the claim that it does. A general theory about oil viscosity reduction when hot doesn't cut it. Then there was a claim that Honda recommended it yet no official documentation of this could be produced.
I think it's important to get the facts straight particularly about something that could potentially damage the most expensive part of your car--that's why we have a forum in the first place. When people make baseless claims let's not pile on the guy who points that out and asks for some data.
Obviously many of your references are really eluding to my comments on the recent track oil thread. If you really had a question, you could just have asked. If you want, I can have Eddie can put you in touch with his Lee and the engineers/employees of Team American Honda Research whom are racing their Showroom Stock B Civic SI's this year at SCCA National run-offs. You can ask them if they go by the factory service manual. Maybe they can explain oil tech to you.
:smile:
) and Honda Switzerland tells them what oil to brew.
Look, this IS the stuff, Honda recommends/fills into Integras, S2000s and NSXs. This has been with my former Integra, my former S2000 and my NSX (until I started working on it myself). 
