Same clearances, different viscosity?

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I have a Honda Prelude which has an H22. The reco'd oil viscosity is 5W-30 and 10W-30, varying by ambient temp. The S2000 uses an F20/22c. That engine has 5W40 (all temps) and 10W30 (above 0) viscosity recommendation from Honda. Since the H22 and F20/22c have extremely similar critical clearances (crank, cam journal, oil pump) and also since the F20/22c has a 10W-30 warm weather reco like the H22, can I assume it'd be within the design parameters of the H22 to use 5W40 in it? The only main difference between the two engines is that the F20/22c uses roller rockers. The reason I'm asking this is that in the last few years cam/rocker failures have started popping up in the H22's (stock valvetrain). Many suspect a potential ZDDP oil deficiency problem. The M1 5W-40 oil seems to have a decent amount of it, and I'd like to use it if it makes sense to. Any thoughts?
 
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JHZR2

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Power density differences, and the resultant heat load on the oil (the engines do put a good amount of 80% of your fuel's heating value into the oil) are a good driver for wanting a heavier oil. Reading into the specs (interesting that a 10w-30 is ok for summer use in the F22), Id guess that for all applications, 10w-30 is OK, but for higher power engines, since 5w-40 drives you to a stable syn oil and 5w-30 drives you to cheap conventionals, they demanded 5w-40 so that you dont use a high shearing, low quality oil and harm your engine in the winter when you want better cold flow... A 10w-30 will have less VII, be more shear-stable, and thus introduce less outside issues. I'd guess that a 5w-40 will be fine for your engine, however, unless there is a benefit (like you have to stock 5w40 for another application which has to have it), why not just go with a quality syn 10w-30 like PP?
 

vinu_neuro

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My car sees the track, so it does have to deal with high-temps, albeit maybe not as high as the S2K. The main reason I wanted to use 5W-40 is M1's 5W-40 and built-in higher amounts of ZDDP, because of cam failures in my engine type in the last few years (since SM). I do use PP in the other car a TL. It has roller-rockers, so I'm not so concerned about SM related valvetrain wear in it. I justed noted that the oil pressure specs are different between these two engines. H22: 10psi min at idle, 50psi min at 3,000 rpm F20c: 36psi min at idle, 85 psi min at 3k rpm Does this have any bearing on the conclusion?
 
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The clearances of the oil pump are not the same as it's operating characteristics. Pressure and flow are what really matters. Add this to various sized orfices , passages, and VVT systems, and you have different oil requirements. Also, they feel the engine will be operated at a hotter temperature, and are accommodating it by a thicker oil.
 

vinu_neuro

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I realize what you're saying. Just from a logic pov, since 10W-30 is shared by both engines for 0*+, is that any indication that a 5W-30 or 5W-40 could be suitable in both engines in terms of pressure and flow? As far as pressure goes, they only set min specs, so if an oil can achieve the spec'd pressure it meets the criteria for that.
 
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There is a pretty wide latitude on oil viscosity for your engine. So in theory anything with a 20 in it or in between (0w20 to 20w60) should work, but some will work better than others. I stick with a good solid all purpose grade--10w30. DISCLAIMER: Except for the 10w30 part, this message is tongue-in-cheek. ;\)
 

JHZR2

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 Originally Posted By: vinu_neuro
I realize what you're saying. Just from a logic pov, since 10W-30 is shared by both engines for 0*+, is that any indication that a 5W-30 or 5W-40 could be suitable in both engines in terms of pressure and flow? As far as pressure goes, they only set min specs, so if an oil can achieve the spec'd pressure it meets the criteria for that.
I agree with you. I can see that a 5w-40 spec would indicate seeing higher temperatures... but 5w-40 is a great year-round oil. Why even bring forth the option of using 10w-30 when temps are higher, if high temps are an issue? I think Honda is afraid of 5w-30 dino going into there because of the high RPM, high shear, high power density (and heat load) engine... 10w-30, even in dino form would likely be robust enough, but 5w-30 would not (which I think can be proven fairly well by typical UOAs). I still think that unless there is a compelling reason to go with a 5w-40, that a good syn 10w-30 should be used year round, which is acceptable to both engines and will be plenty robust.
 
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 Originally Posted By: vinu_neuro
I have a Honda Prelude which has an H22. The reco'd oil viscosity is 5W-30 and 10W-30, varying by ambient temp. The S2000 uses an F20/22c. That engine has 5W40 (all temps) and 10W30 (above 0) viscosity recommendation from Honda. Since the H22 and F20/22c have extremely similar critical clearances (crank, cam journal, oil pump) and also since the F20/22c has a 10W-30 warm weather reco like the H22, can I assume it'd be within the design parameters of the H22 to use 5W40 in it? The only main difference between the two engines is that the F20/22c uses roller rockers. The reason I'm asking this is that in the last few years cam/rocker failures have started popping up in the H22's (stock valvetrain). Many suspect a potential ZDDP oil deficiency problem. The M1 5W-40 oil seems to have a decent amount of it, and I'd like to use it if it makes sense to. Any thoughts?
If your wanting to stick with Mobil 1 products, either the 0W-40 or the HM 10W-30 should work for you. Both have higher levels of zddp. See the attached chart. http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_Product_Guide.pdf
 
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I vote for the M1 HM in either the 10W30 or the 10W40. Both are still SL rated, not SM, and I now use the 10W30 version in both my 2005 Pathfinder and all of my OPE, since the 5W30 versions of M1 are only available in SM.
 

vinu_neuro

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JHZR2: I just played around with the viscosity calculator and looks like I'd get better start-up protection with 10W-30's than the 5W-40, and better start-up with the 0W-40 than the 10W-30..in terms of picking an oil out of the M1 line-up that satisfies what I'm looking for in an oil for this car. Johnny/1999nick: I actually historically dislike M1 for many reasons, but they seem to giving customers SL and SL/SM oil which is what I want in my Prelude. The 10W-30 HM seems ok, but is it dino? That won't do on the track. Penzoil Platinum is great and I use it in the other car, but it's SM also. Are there any quality SL synthetics still out there?
 
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The viscosity calculator should be taken as an estimate only for non-newtonian oils. It is not accurate unless there are no VII's in the fluid. Synthetic 5W40 or 0W40 will provide decent cold start-up protection. A good synthetic 10W30 should be fine as well. It really depends on the specs of the actual oil that you will be choosing. You can look these up (such as pour point, CCS values, etc) on the manufacturer's websites.
 

JHZR2

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right... In reality, while a 5w- or 0w- oil is really designed for super-low temperature startup (by test specification), the reason we have gone that route is because of incrementally better flow at cold start - yielding better fuel economy. The bettr flow gets stuff working together faster and better - and good flow at the start is key. You still cannot go wrong with a syn in either viscosity.
 

vinu_neuro

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 Originally Posted By: JHZR2
right... In reality, while a 5w- or 0w- oil is really designed for super-low temperature startup (by test specification), the reason we have gone that route is because of incrementally better flow at cold start - yielding better fuel economy. The bettr flow gets stuff working together faster and better - and good flow at the start is key. You still cannot go wrong with a syn in either viscosity.
I spent some time reading and came across Terry's raving comments about PP. I trust his opinion to just follow it. He's specific about 10W30, which I don't entirely understand. Can there be a big difference between 5w30 and 10w30 in how they do their job? If a 5w30 will work just as well, I'd rather use that. So if the viscosity calculator doesn't work for most oils, is the only way to find oils' viscosities at other temps, to contact the company?
 Originally Posted By: Terry
Pennzoil Platinum 10w30 is one of the most stable, low wearing lubricants you could purchase right now from a Major formulator. The additive package is very advanced and does NOT rely on ZDDP to make it work in boundary and mixed lubrication regimes. High Valve Spring Loads are not a scary thing for this chemistry. Shell is turning it up a few notches and this is but one example. I have no doubts your VT noise is less. I see plenty less VT wear in my customers running this oil.
 
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 Originally Posted By: vinu_neuro
I spent some time reading and came across Terry's raving comments about PP. I trust his opinion to just follow it. He's specific about 10W30, which I don't entirely understand. Can there be a big difference between 5w30 and 10w30 in how they do their job? If a 5w30 will work just as well, I'd rather use that. So if the viscosity calculator doesn't work for most oils, is the only way to find oils' viscosities at other temps, to contact the company?
The company likely won't have any information about viscosities at temperatures other than 40 C and 100 C. Those are the standard measured temperatures required for calculating viscosity index. My opinion on Terry's comments is that they are not applicable to the other grades of PP. He specifically states the 10W30 and I would take it as that. The PP 5W30 may not have the same shear stability under tough usage. That's not to say that there isn't another synthetic 5W30 that is highly shear stable. I personally would have absolutely no reservations about using a 10W30 synthetic oil because most of them have very low pour points and great flow at cooler temps (not that I would use it in the dead of a Canadian winter, but "cool" temps would be okay).
 
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