SAE 20W

[Oil_Can_Harry]

I found a site with a bunch of literature related to old automobiles. One of the items there was an owners manual for a 1940 Chevrolet. The interesting thing about the manual was that it pretty much recommended 20W oil year round with the exception of very cold weather when 10W was permitted. The following link reference the page with the oil recommendation in the 1940 Chevy manual

http://www.tocmp.com/manuals/Chevy/1940/Owners/pages/40om44_jpg.htm

This link is the general link to the site. Lots of really neat old literature on old cars

http://www.tocmp.com/

 

[G-MAN]

20w20 was pretty much the factory fill in Detroit until the late 50s/early 60s when they started using 10w30.

 

[G-MAN]

Look at item 15 from this 1956 Ford owner's manual:

 

[oilyriser]

My car has 20w-20 in it right now.

 

[TallPaul]

My F150 has 20w40 in it right now. I blended it by mixing Valvoline 20w with Valvoline 20w50.

 

[TR3-2001SE]

Maybe this explains why my Dads 57 Ford was alway out of oil when I checked it. Also expains why it didn't last long and had to be rebuilt before it hit 50,000.

 

[1999nick]

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Maybe this explains why my Dads 57 Ford was alway out of oil when I checked it. Also expains why it didn't last long and had to be rebuilt before it hit 50,000.

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I'll guarantee that the 20 weight oil was not the reason. I had a 1954 Ford V-8, bought new in '54 by my Dad, which I used to commute to college for a couple of years, and then did an Army commute for the next three years. I was stationed 330 miles from home, and shortly afterward acquired a girlfriend in my hometown. I did that 660 mile roundtrip about 40 times a year until I got discharged in 1959. By that time, my 1954 Ford was sitting on 140,000 miles, was running good, did not smoke or use oil, and had never required a valve adjustment. It had always used Sinclair 20W20 motor oil. In those single grade oil days, it was the usual practice to change over to 30 weight if your engine began to use oil, but my engine never did. I don't know how long that engine lasted, because as soon as I got out of the army in 1959, I traded it off.

 

[Oil_Can_Harry]

Exactly the point. For the past 40 or so years we were on a light oil is bad kick. When Ford and Honda started recommending 5w-20, the doomsday crowd started predicting everything from destroyed engines to baldness and frigidity of the bowels. Fast forward 5-6 years and it ain't happened yet. Cars in the 40's and 50's did not automatically disintegrate with 20W oil and the oil then was nothing near as good as the oil today.

 

[Steve S]

What were the engine operating temps? 160 thermostats? Heavy duty real over engineered parts low power output per cubic inch. Emission controls wern't invented yet. Light oil is not good or bad if it correct for the application.An oil has to be thick enough to keep the parts seperated but not too thick as to cause a power loss.

 

[Lonnie]

Different times, different driving condidtions, different everything. 20w-20 was rally common in those days. Average speeds were down and as SteveS mentions operating temps were lower. I would say that engines did not last as long and more maintenance was required to keep them running. The common valve job done then is reason to sell a car now. Most of todays tech's never do a 'valve job'. Ownership today is a much different experience.

 

[TallPaul]

Also, I wonder if the 20w20 didn't have a higher HTHS than today's 5w20s?

 

[Camu Mahubah]

Many 5w20 users could get away with a straight 20w in warmer climates.

 

[bruce381]

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Also, I wonder if the 20w20 didn't have a higher HTHS than today's 5w20s?

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with no VII i'd sya yes

 

[oilyriser]

2.9

 

[1999nick]

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Also, I wonder if the 20w20 didn't have a higher HTHS than today's 5w20s?

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I don't know about today's 5W20, but I just checked the owner's manual of a 1980 Pontiac Bonneville I owned from 1980 until 1986, and it lists 9 different weights of oil that would be satisfactory, depending on the temperature.

It lists 5W20 as being OK from -20 to +20 degrees. It lists 20W20 as being OK from +20 to over 100. Seems that GM did not really have much trust in the 5W20's of the early 80's.

 

[G-MAN]

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It lists 5W20 as being OK from -20 to +20 degrees. It lists 20W20 as being OK from +20 to over 100. Seems that GM did not really have much trust in the 5W20's of the early 80's.

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A 5w20 made from Group I would be suitable only for low temperature use. The advent of Group II and Group III base oils is what enabled car manufacturers to specify 5w20 for year-round use.

Remember, when Mobil 1 was introduced it was a 5w20. The PAO base oil is what enabled Mobil to recommend this for year-round use in vehicles that normally saw 10w40.

 

[1999nick]

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It lists 5W20 as being OK from -20 to +20 degrees. It lists 20W20 as being OK from +20 to over 100. Seems that GM did not really have much trust in the 5W20's of the early 80's.

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A 5w20 made from Group I would be suitable only for low temperature use. The advent of Group II and Group III base oils is what enabled car manufacturers to specify 5w20 for year-round use.

Remember, when Mobil 1 was introduced it was a 5w20. The PAO base oil is what enabled Mobil to recommend this for year-round use in vehicles that normally saw 10w40.

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I well remember that Mobil 1 was 5W20 when first introduced. It was stated to be the equivalent of 10W40 regular oil. It was also stated to be good for a 25,000 mile or one year OCI. I used Mobil 1 from the time it was introduced until 2001, when I retired and went from driving 18,000 to 20,000 miles a year to around 6,000 miles a year. I always used a one year OCI while using M1. Back then, I had never heard of UOA's. I never had any oil related problem, although I only put as much as 140,000 miles on one car while using M1. As a matter of fact, I have put 140,000 miles on only two cars in my lifetime, my 1954 Ford using 20W20 dino being the other. That car was treated to several oil changes a year, however.

 

[JohnBrowning]

Engines also had to be rebuilt or at least re-ringed by 36,000-50,000 miles. They also used leather and rope seals not to mention laqured paper. I donot see anyone jumping on the bandwagon to go back to poor seal materials! 20W20 caused the black death in Europe on Adam Opel products like crazy!

You can still find 20W20 but I would not use it in anything I own!Well I might try it in a lawn mower or something like that!

 

[G-MAN]

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You can still find 20W20 but I would not use it in anything I own!Well I might try it in a lawn mower or something like that!

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A modern 20w20 that meets API SM would be fine to use at reasonable OCIs in any car calling for 5w20 or 5w30.

 

[1999nick]

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Engines also had to be rebuilt or at least re-ringed by 36,000-50,000 miles. They also used leather and rope seals not to mention laqured paper. I donot see anyone jumping on the bandwagon to go back to poor seal materials! 20W20 caused the black death in Europe on Adam Opel products like crazy!

You can still find 20W20 but I would not use it in anything I own!Well I might try it in a lawn mower or something like that!

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Come on, John! What era are you talking about, anyway? These 36,000 to 50,000 mile overhauls might have been par for the course in the 1930's. and maybe for some cars in the 1940's, but the 1950's cars, for the most part,had new families of overhead valve engines, sixes and V-8s that were good for at least 150 to 200,000 miles. I have recounted my experience with my 1954 Ford several times on this forum, using 20W20 motor oil. It was about 1955 that one of my college roommates had a 1951 Oldsmobile. It was getting ready to turn over 100,000 miles, and we celebrated this milestone by taking it out on the highway and having it turnover the 100,000 mile mark while doing 100mph.

In my opinion, 20W20 oil would serve most of todays cars very well, especially in warmer months. As I mentioned above, it was one of 9 different oils that were recommended in the owner's manual of my 1980 Pontiac Bonneville, which I had from 1980 until 1986.