M1 0w-40 in '98 SHO...?

[3xSHO]

I'm having a discussion with my SHO colleges with respect to using Mobil 1 0W-40 in my '98 SHO (3.4 liter V8). The majority of the responses are that I should not be using such a 'heavy wt' oil given the very close tolerances and bearing clearances in this engine. Factory recommendation is 5w-30, which I normally use(Mobil 1).

Rod

 

[buster]

Well, if your not having any consumption problems, I'd stick with 5w/10w-30. You can run the 0w-40 in any car that calls for a 30wt oil. To play it safe, wait until the warranty is over, which in your case it should be. I'm thinking of running the 0w-40 myself bc I have 110k miles and my car is drinking 0w-30 right now. I think this oil would be good in this situation bc if it does thin out, it will be a solid 30wt. oil. So all in all, if consumption is not an issue, I'd stick to what you were using.

 

[Steve S]

What will using 0w40 do to the engine? Using 20w 50 will be noticeable its really thick but 0w40 not much difference. Are we saying 40 wt will not squeeze through the bearing clearances? We want to use the thinnest oil that will keep the engine parts seperated during operation.

 

[Patman]

From what I have read about the SHO it does use rather tight clearances, so I think that Mobil 1 0w40 might be too thick for best protection. M1 0w40 has a viscosity of about 14.4cst at 100c, so it's a middle 40wt.

What I would suggest is that if you've got a bit higher mileage on your engine, is to step up to a 5w30 which is formulated thicker than Mobil 1 is. Mobil 1 5w30 has a viscosity of 9.7cst at 100c, so it's not far off from being a 20wt oil. I'd suggest something like Amsoil, Royal Purple or Redline, all of which are thicker 5w30s. Amsoil 5w30 is 11.7cst, RP is 11.4 and Redline is 10.6. If you drive very hard and don't mind spending a bit extra, Redline is your best bet here.

 

[3xSHO]

Originally posted by Patman:
What I would suggest is that if you've got a bit higher mileage on your engine, is to step up to a 5w30 which is formulated thicker than Mobil 1 is. Mobil 1 5w30 has a viscosity of 9.7cst at 100c, so it's not far off from being a 20wt oil.

Would you recommend M1 0W-30 with it's higher VI (176) and 10.1 cSt @ 100°C over M1 5W-30? My SHO only has 50k km. on it...

 

[jason07-1zzfe]

No M1 0w30 actually has a thinner film thickness than the 5w30 and 10w30.

 

[Tommy2]

I also own a SHO but mine is a '95. The '95's came with the V6 engine. The v6 has tight tolerances also and Patman chose to subscribe Redline 5w-30 oil because it's viscocity at 100ºC is 10.6cst.
Is it safe say then that Castrol oil is as "good" as Redline? Castrol's viscocity at 100ºC is 10.7cst.
(Probably a dumb question)

 

[unDummy]

http://www.shoclub.com/lubrication-oil/lubrication-oilpart1.htm
http://www.v8sho.com/SHO/Oil Choices & Additives.htm
http://www.shotimes.com/SHO3synthoil.html

Unless your engine is an oil burner(clearances opened up and engine worn), stick with the 5w30 Mobil1 or other quality synthetic.

If you have minor oil burnage, then you could use the 5w30 as the fill oil during the change and 0, 5 or 10...w40 as the regular topoff. This should make up for any oil breakdown, help reduce/control oil burnage, and shouldn't affect those supposedly tight clearances or MPG/HP.

 

[Patman]

quote:

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Originally posted by -Tommy-:
I also own a SHO but mine is a '95. The '95's came with the V6 engine. The v6 has tight tolerances also and Patman chose to subscribe Redline 5w-30 oil because it's viscocity at 100ºC is 10.6cst.
Is it safe say then that Castrol oil is as "good" as Redline? Castrol's viscocity at 100ºC is 10.7cst.
(Probably a dumb question)

---

Viscosity is only part of the equation though. I should've elaborated more that the HTHS number is more important. Even though GTX is the same viscosity as Redline, it's got a much lower HTHS number (3.1 vs 3.8) So under extreme use the Redline will hold up better. That's not to say GTX isn't very good, just that Redline is a much technically better oil. GTX still shows good UOAs on here though.