20 Weight Oil

[2004 F150 4x4]

Thought you guys might mind this interesting:
From the 1956 copy of Motor Service's NewAutomotive Encyclopedia
"The car manufacturer recommends the weight of oil to be used in his cars under various conditions. This recommendation is based upon the existing temperature and the clearances existing in the engine. Thus a new engine built with close fitting parts might use an SAE 20 oil in warm weather and change to a 10-w in cold weather for light service. In extreme cold a No. 5-w oil might be required for easy starting. Anyhoo thought it was kind of interesting myself.

 

[mikemc]

I was reading the owners manual to a 1972 Ford C650 with a 391 v8. 20w20 was recommended for cold weather, straight 30 or 40 for warm weather.

 

[buster]

I still believe in that Steve Bergin article where he states viscosity isn't that relevant. Basically it comes down to what you just quoted- engine type, conditions, temperature and quality of oil. Some think by just switching to a thickery viscosity will cure all their problems. It's more involved then that. At times it can make a difference but it's important to look at everything as well. For 1956, thats pretty **** good!

 

[427Z06]

Yes buster, your ahead of most when it comes to being pragmatic. People from the recent past aren't as dumb as some might presume. Some of the basic physics involved in lubrication are almost a century old. And remember, the Romans invented concrete.

 

[ekpolk]

Whoa guys, we need to clarify what Bergin said. My take on it is that viscosity was not really an issue unless dealing with temperature or operational extremes. I Googled for the article itself, but could not find the text directly. I did find a review however that contained this description of what Bergin did say about viscosity, "Bergin followed up with a qualification. "Viscosity is not an issue [in cases] where extremes of either temperature or high load service do not exist.""
This quote came from http://www.lubes-n-filters.com/newsletters/advertising.html . Note that from all of what he says, vis is important, at both temp/use extreme, and vis extremes as well (i.e. do not use 20w-50, presumably for engines that spec a much thinner oil).

 

[427Z06]

ekpolk, I think we're all in agreement with that, at least I am. Running 20w50 conventional racing oil in a tightly clearanced engine in -40F weather for mainly short trips will surely cause problems. Just as running a shear prone 5w30 cheap dino in a loosely clearanced race car with oil temps over 300F for 500 miles will likely cause problems. But in a daily driver not subjected to such extremes, the difference between a 9cSt@100C quality multi viscosity oil and an 11cSt@100C quality multi viscosity oil, will almost certainly not effect the life of the engine if the proper OCI for the selected oil are practiced.