Originally Posted By: jrustles
Originally Posted By: snowflake
If you can show me how a straight 30 protects an engine better for a daily driven passenger
the criterion in the case of your question, is "protect", presumably the best protection.
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Do you really think a company would make a suggestion on a lubricant that wasn't adequate? They have (had) in this case to warranty it.
see how quickly it turns into an issue of adequacy?
we're not arguing that to achieve a suitable cold pump rating will yield less than adequate viscosity or deposit protection, it clearly is adequate- but not necessarily 'the best'.
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If you really want to run a straight 30 weight, go right ahead, I really don't care, its your vehicle. But it is not going to provide superior protection over a 5w30, and still won't provide superior flow at cranking.
Do you really think a company would make a suggestion on a lubricant that wasn't adequate? They have (had) in this case to warranty it.
I haven't run SAE30 in about a decade, but certainly would, particularly in an aftermarket turbo engine- or any engine in a warm/hot climate, really. Although a minimally vm'ed synthetic 10w30 (like a sopus gtl 10w30) would be my premier choice. you bet if i had a DI engine, it'd be something like that, barring frigid temperatures.
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You sound an awful lot like the people who say 5w20 won't work in Ford modulars because its not thick enough when Ford punishes the engines in extreme heat on just that, 5w20, and determined that it is adequate.
first, 5w20 is perfectly fine for modulars. 'punishing' a low power density engine isn't really punishment in my opinion, and 5w20 mineral oils are among the "straightest" of the multi-vis oils, akin to 10w30 straightness!.
modulars were designed for longevity, have you seen the size of a modular sohc camshaft base circle? it's huge. now how about a high power density ford v8 like the boss or even the 5.0gt without the oil squirters? 5w50 is a pretty big jump from 5w20, is it not?
and yes, i know what i sound like. i know the kind of ideologies that
some people immediately associate simply because i'm not bad talking straight grades and worshipping vi, but that's my prerogative to not be blinded by dogmatism, to maintain a balanced and as bias-free view on the issue, not because i balk at modern lubes. no matter how i or anyone else romanticizes of interprets a type of engine oil; their respective pros and cons will not change because of it.
for example, out of the fleet that i maintain, none currently have anything thicker than a 20grade in applications that call for 5w30, with the exception of a synthetic 40 grade in a supercharged Jaguar V8. why? with the exception the 0w20 filled, 8K redlining v6 engine, the rest are relegated to light duty in colder canadian climates.
i've been running 0w20 in an all original atmospheric engine, designed in the late80s, early90s that was manufactured in 1994 that sees 8k rpm regularly. why? because of the way it specifically was manufactured. back then, heavy-duty rolled, high frequency hardened bearing fillets and mirror finishes on forged steel crankshafts wasn't too common on standard production engines, as they are now. plateau honing and precise robotic engine assembly wasn't so popular yet. further, the bearing journal on this engine are larger in diameter and shorter in width than average, so the shear speed is higher for a given crankshaft rpm, while allowing a decent 'leakage/refresh rate'; perfect for low vis oils IMO. with the exact same crankshaft utilized in a supercharged version of the engine series, the larger than average bearings and quality finishes are kind of 'overkill' for an NA engine. also, the #6 bearing can see a higher pressure drop than the other, IMO, if the resistance to flow is too high.
i had to draw all these conclusions myself- no one is going to personally optimize my lube choices for me.
interesting note, the last straight grade i ran was Esso XD-3 20w20 SJ in a toyota 2.2, maybe 5-6 years ago. it ran great, quiet with no hit on fuel economy. no issues. it seems like forever ago, but you'd never know just because i'm not pushing the highest VI "EC" (HTHS limited) oils as the panacea or the end all and be all- those aspects already have plenty of representation here
Now you are talking and debating in a fashion that I can relate to
I seriously (could be wrong, it happens) doubt that a straight 30 will provide better deposit and protection against viscosity break down than a 5w30. Of course, without any hard data I can't physically prove it. I do not debate that oil shears out of grade, but usually it doesn't hurt anything. When was the last time any oil maker even made a change to the straight grade? I can only find Castrol and Pennzoil SAE30 here, and no bottles handy as I have no need for it. I would be curious the API spec, I think someone should do a VOA
DI is a new beast, depending on what engine is in the trooper originally debated, it may have a (although its been a while, I don't think it was out in 00, came out in 04 iirc)DI 3.5, which as I mentioned earlier, although impressive for the time period, was problematic, I've always understood it that the engine ran a bit hotter than most, coupled with to few oiling holes on the pistons, resulted in plugged holes and thus oil burning. A synthetic 5w30 (or by my own admission 10w30 although not the prefered grade) would be the way to go in his engine in my opinion/experience) which is reflected in the book for his car.
I work with Modulars almost every day, since my employer has tons of them, great engines
Although if I recall correctly the last Mustang with a 5.0 I looked at was a 5w20 car too.
The fleet of vehicles, outside of my signature, which includes a rodeo with a 3.2l, a Ford 428, Porsche 911, Ford 6.0 PSD, to name a few that I maintain, all goes awfully far on the recommended grade, can their be better? yeah, I suppose so, but on the flip side of the coin there can also be worse, which can result in things a UOA can't pick up.
The last time I used straight 30 was in the VW air cooled engine I built for my sandrail, its been done for nearly a decade now and I haven't even put enough miles on it to consider it "broken in"
My final thought? will other oils (including SAE30) work? Yeah, probably, are they/can they be less than ideal? Yes.
