Oil to use?

[CDOW]

Hello, I have a stock 1950 Custom with a flathead 239. The original service manual calls for straight weight 20W oil. I can't find that anywhere and was wondering what modern grade of oil would be best to use instead. It has no oil filter. Thank you!
Craig

[JayChicago]

From what I have read here, most say any modern oil will do just fine. All of today's oil is better than what was available in 1950. No need to use straight weight. Probably should use 20W-30 or 20W-40. It's viscosity is 20 weight when cold, and the higher rating when hot will not hurt, only help the engine.

[Talkwrench]

What climate are you in ? If its like California or similar a 20-50 wt mineral of good quality and some level of ZDDP will be fine and non detergent would be better if no filter . Dont get to carried away whatever you use will be far better than was available in its day..

[G.M.]

There have been a lot of tests done by oil engineers that are on line.
Most of these guys don't have a dog in the race so they look like honest
answers. They list 6 or 8 oils and rate them 1 to 8 I have one I use that
tested 23 diesel oils. They also list the ingreediants. G.M.

[CDOW]

Thank you, all, for your advice and information. Very helpful and I appreciate it!

[tubman]

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Originally Posted by Talkwrench

What climate are you in ? If its like California or similar a 20-50 wt mineral of good quality and some level of ZDDP will be fine and non detergent would be better if no filter . Dont get to carried away whatever you use will be far better than was available in its day..

I'm sorry, but I have to disagree with this as a blanket statement. Perhaps, in some cases (such as an old, tired, sludged up engine), this may be true, but for just about every other situation, a detergent oil is better. If you're not going to run a filter, just change the oil more frequently. As to what particular oil you should use, I buy whatever is cheapest (10-30 or 10-40) on sale at the closest discount store. As was also said in the previous post "whatever you use will be far better than was available in its day".

[JSeery]

Originally Posted by CDOW

Hello, I have a stock 1950 Custom with a flathead 239. The original service manual calls for straight weight 20W oil. I can't find that anywhere and was wondering what modern grade of oil would be best to use instead. It has no oil filter. Thank you!
Craig

You may already know this, but "w" stands for "winter" not "weight". Oil viscosity in general is rated on two different temperature scales, a higher scale (212 deg) and a lower, "winter" scale (0 deg). This new multi-grade standard was adopted around 1952. Prior to that is was common practice to run what was considered to be summer oil/gear lube (a higher viscosity) and winter oil/gear lube (lower viscosity), which was based on the operating environment. Such as for engine oil:

Above 90 deg SAE 40
Above 32 deg SAE 30
Above 10 deg SAE 20
Above -10 deg SAE 10

And for gear Lubricate:

Summer SAE 140
Winter SAE 90

There are many advantages to modern oil blinds and multi-viscosity is one of them.

[19Fordy]

20w50

[VeryTangled]

My specialty recently is left turns... Don'tcha just love a FordBarn classic topic?

[39portlander]

Your right Jeff, I thought this might be a belated "April fools" joke but I'm with 19fordy on this one the 39 and "Big Blue" my 77 F150 love the 20W50.

Hey man @ the NAPA in those 5 quart juggy things it's always on sale

[TedEaton]

The reason for using non-detergent oil in a non-filtered engine is so that the contaminates in the oil drop to the bottom of the pan rather than be carried in suspension where those contaminates can get recycled through the engine repeatedly. On an engine with a full flow oil filter, detergent oil allows the contaminates to be carried in suspension thus allowing those contaminates to be filtered out of the oil before going to the bearings.

[Jack E/NJ]

Heh-heh. You forgot the sludge at the bottom of the valley and half way up the sides too. 8^) Jack E/NJ

[39portlander]

Originally Posted by CDOW

Hello, I have a stock 1950 Custom with a flathead 239. The original service manual calls for straight weight 20W oil. I can't find that anywhere and was wondering what modern grade of oil would be best to use instead. It has no oil filter. Thank you!
Craig

Hey Craig post a picture of that custom, we like pictures here on Fordbarn.

There is a nice 1950 custom fordor on the back page of the latest V8 times, if you are not a member yet please join and support the Hobby brother

[40 Deluxe]

Originally Posted by TedEaton

The reason for using non-detergent oil in a non-filtered engine is so that the contaminates in the oil drop to the bottom of the pan rather than be carried in suspension where those contaminates can get recycled through the engine repeatedly. On an engine with a full flow oil filter, detergent oil allows the contaminates to be carried in suspension thus allowing those contaminates to be filtered out of the oil before going to the bearings.

What I've learned over the years is that the"contaminates" that turn oil dark are acidic combustion by-products ("blow-by") that are too small to be trapped by a filter. Same with the dust that hangs in the air on a gravel road. Since a filter won't trap them anyway, why not use a modern detergent oil that has a number of other beneficial additives? Remember, if it's non-detergent it will not have any zinc in it.

If your engine is producing "contaminates" large enough for a filter to trap, you've got other problems! Like it's making metal or the oil fill cap is gone.
I suspect (just my opinion at this point, haven't researched) that a major reason for oil filters on newer vehicles is to catch any trash left over from the manufacturing processes or that flakes off during the warranty period.

[Talkwrench]

You will find olis with very low detergents but with zinc. Pentrite Shelsley for example.

[blucar]

Many years ago when I had my own business we had several stationary engines that ran pumps, generators, and cement mixers, the majority of which were Kohler, or Wisconsin, single cylinder, twin and/or V4's.
We always used non-detergent 30w oil in the engines. We generally had the engines rebuilt in lieu of buying a replacement engine. Starting sometime in the early '70's the machine shop that rebuilt our stationary engines started asking us if we wanted babbit or insert bearings in the engine, the first time I was asked this question I wanted to know whats the difference? The reply, babbit bearing cost more, do to the added labor, the conversion to inserts is cheaper. Babit bearing require non-detergent oil whereas with inserts we could use detergent oil in the engine.
We generally purchased oil, 20/50 GTX Castrol in 50 gal drums because it would work in all of the vehicles, including the diesels.
I used GTX in my '36 Ford from the early '70's until about 10 years ago when I switched to Shell Rotella, Delo or Valvoline for diesels. usually 10-40..

[40 Deluxe]

"Babbitt bearings require non-detergent oil"?? Why? Did this machine shop explain? After all, many insert bearings have a thin Babbitt layer that works just fine with detergent oil! This sounds like another myth.

[Karl]

I use 20w-50w detergent oil - Mostly because its easier to get
I have no filter and I change the oil every 1000 miles . Every time I've had the inlet manifold off I'm amazed at how clean the valve train is No sludge at all . However I suspect the most crucial factor is the frequency of oil change rather than what oil I am using -Karl

[philipswanson]

30 weight Rotella with some MMO. Multi viscosity oils like 10W 50 leak too fast because when cold they are too thin. Early flathead main seals are not so good. Earliest ones don't even have a main seal, only a slinger.

[G.M.]

The clearance of the bearing on the shaft determines amount of oil leaking
out of the crank shaft. I pumped 40 lbs of oil into the system with the pan
off and had very little oil leaking from the bearings. Oil was leaking from
weak bypass spring in pump. G.M.