30 or 40 weight vs. 10W-30 or 15W-40

[BuickGN]

Originally Posted By: mechtech2
Even in summer, you have to start a car.
And good flow is very important. A straight 50 is silly.
Not only too thick at starting, but at intermediate temperatures.


I agree with you mostly. But for the sake of argument and in bitog fashion, define "too thick at starting".

My only point here is that pressure and flow are nearly instant no matter what oil you use as long as it's acceptable in the climate it's used in. No reason to go thicker at startup when thinner ones are available but I don't necessarily agree with giving up HTHS for thinner startup vis in an engine that never sees freezing temps in the winter and is constantly operated in 100F weather in the summer.

I would not run a straight 50 unless it was something like Redline straight 50 which is more than likely a 15-50.

 

[Zaedock]

I use straight 30 three seasons a year. Picked up a bunch of Delo SAE30 about 5 years ago for $.99/gallon. The specs are nice with a PP about equal to a 10W30 and a robust 12.1 cSt operating viscosity. The TBN of 10 makes for a nice $4.00 oil change.

 

[mechtech2]

BuickGN - Lubro Moly had tests where cold flow to remote pats of the engine were measured. [nothing to do with their actual product]
I posted it somewhere.
It showed a huge difference from light to heavy oils.
[A quick search and Google failed to find this link.]

 

[BobFout]

Originally Posted By: mechtech2
BuickGN - Lubro Moly had tests where cold flow to remote pats of the engine were measured. [nothing to do with their actual product]
I posted it somewhere.
It showed a huge difference from light to heavy oils.
[A quick search and Google failed to find this link.]


Is this the picture in question?

 

[BuickGN]

I appreciate you guys posting the chart and my argument is in no way with you guys. But that chart is complete and udder [censored].

I've been an oil nerd for years and I've watched engines with the valvecovers off, started them with a 20w-50 in slightly colder than 0C and watched for flow to the top end.

With everything I've ever run in almost every engine I've ever tested, pressure light goes out pretty much immediately and I can see flow to the valvetrain within a second. I've left my turbo feed line off by accident and ended up with 20w-50 dino on my windshield as I released the starter in the winter.

The only way this chart *might* be true is if you were starting with an unprimed brand new engine with empty oil galleys and even though it's questionable.

 

[mechtech2]

Thanks Bob Fout!
You must be a cop!

Buick GN - Why reject their testing? I know for sure that thick oil flows slower , esp on start up.
I have empirical evidence of oil pressure lights and gauges that go out faster on start up with thinner oils.
Plus, it it just common sense.
OHC bearings count!

 

[BobFout]

Originally Posted By: mechtech2
Thanks Bob Fout!
You must be a cop!

Buick GN - Why reject their testing? I know for sure that thick oil flows slower , esp on start up.
I have empirical evidence of oil pressure lights and gauges that go out faster on start up with thinner oils.
Plus, it it just common sense.
OHC bearings count!


Ha no! I do have "cop hair" though

(the Chevy Malibu commercial)

 

[Steve S]

There is residual oil on the parts so unless you have the wrong visc oil your O.K. Buick GN is correct.

 

[aquariuscsm]

I`m with Buick on this one.

 

[aquariuscsm]

This is probably something that`s been covered a million times,but what`s the exact difference in say,a 5W50 and an SAE50? In layman`s terms,how exactly is the makeup of the oil different and which one is the more "high quality" oil?