What oil to use?

[Solo_909]

I’m sure this has been asked a million times. I’m going to change the oil in my 37 flathead but forgot what I used last time. What should I use? I think I used some hotrod oil from Lucas last time. If you recommend a certain weight can you also say why so I can gain education?

[FrankWest]

Oh no, asking about oil on this thing can be dangerous. If it is a rebuilt engine use any oil you like if un-rebuilt us only non detergent oil.

[Talkwrench]

Yes a million times and a million different answers.. Personally if its in good condition a good quality mineral 20 - 50 is as good as any.. and I dare say you don't have any filtering system so change regularly .

[JSeery]

This is like asking what is your favorite color and why!

[Frank Miller]

I used Mobil 1 with great results but I'm wondering if anything else might have done the same? Before that I was running conventional oil 10-40. If you change it every year and drive less than 6000 miles I feel confident telling you that will be fine. Check the oil by the numbers thread.

[firerod]

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I use Castrol 20w-50.

[ct1932ford]

Valvoline VR1 Racing oil w/zinc. I use 20/50

[Ol' Ron]

I use any good quality 10-30 oil, which was recommended by Ford (10 winter , 30 summer) the heaver oils are for engines with larger bearing clearances and in a good engine will run hotter. Oil should flow through the bearing removing the heat.

[FrankWest]

No matter what oil you use add some Marvel Mystery Oil

[Jeff/Illinois]

Originally Posted by Ol' Ron

I use any good quality 10-30 oil, which was recommended by Ford (10 winter , 30 summer) the heaver oils are for engines with larger bearing clearances and in a good engine will run hotter. Oil should flow through the bearing removing the heat.

Ron how about 5W-30, that should be OK, right? Reason I ask is, it is cheap at WalMart in a 5 qt. jug, the 10W30 you have to buy buy the quart costs twice as much they don't have it in 5 qt. containers anymore for the brand I use.

[Ford coupe]

After reading up on the issue on Ford Barn several different times I decided on Rotella diesel 15 40 in my 55 272 and my 36 flattie and am well pleased..I find myi55 which leaked a quite a bit at rear seal hardly leaks at all so keeping fingers crossed Also use it in my riding mower tiller and atv..Well pleased..

[Ol' Ron]

I don't feel that the viscosity of the oil can be judged by just installing it in an engine and just crossing your fingers and hopping the engine is running OK. Engine designers specify the viscosity of the oil needed to properly lubricate their engine under normal use. To say 15-40 works fine is not a fact, just an opinion. I will say, it makes the oil pressure gauge read higher, which makes the driver happy.

[Frank Miller]

Ron,
Check out this article. I agree with what you said about manufacturer recommendations but sometimes the engineers learn stuff they never knew.
https://www.blackstone-labs.com/News...ary-1-2017.php

[JSeery]

Ol Ron has posted his insights on oil viscosity several times on the Barn and I'm not sure it is being totally understood. Oil serves more than one function in an engine. Oil under pressure is forced between metal surfaces within an engine to prevent metal to metal contact. As long as the clearances are tight enough this oil film supports the loads. If the clearances get too loose the oil film can not preform it job and some metal to metal contact occurs. Race engine are deliberately built with loose clearances and require a heavier viscosity lubricant. But, an additional very important function of the circulating lubricant is to carry heat away from the metal surfaces it comes in contact with. This function depends on it's ability to move quickly between the surfaces and back to the oil pan. So for the lubricant to work at an optimal level it needs to both support the loads to prevent metal contact and move a quickly through the system as possible to carry away heat. A thick viscosity lubricant in a tight tolerance engine limits it's ability move through an engine quickly and reduces it's effectiveness. High oil pressure readings are not necessarily a good thing.

[Ford coupe]

I did not install 15/40 Rotella because of the viscosity but because of the quotes on this site which were all good or mostly good..Now if I could have got 10/30 in Rotella I would have preferred that viscosity..I also liked the idea that it had a small amount of zink in it...Don't know if it still does..If I were to put manufacturers recommended in my 36 I would need 30 non detergent which id nearly impossible to get so I just picked what I hopefully think in a good oil for the vehicles Thanks barners and

[40cpe]

Originally Posted by Ford coupe

Now if I could have got 10/30 in Rotella I would have preferred that viscosity.

My Kubota tractor specifies 10w30. I found Rotella T5 synthetic blend diesel oil at my local WalMart.

[Frank Miller]

Originally Posted by JSeery

Ol Ron has posted his insights on oil viscosity several times on the Barn and I'm not sure it is being totally understood. Oil serves more than one function in an engine. Oil under pressure is forced between metal surfaces within an engine to prevent metal to metal contact. As long as the clearances are tight enough this oil film supports the loads. If the clearances get too loose the oil film can not preform it job and some metal to metal contact occurs. Race engine are deliberately built with loose clearances and require a heavier viscosity lubricant. But, an additional very important function of the circulating lubricant is to carry heat away from the metal surfaces it comes in contact with. This function depends on it's ability to move quickly between the surfaces and back to the oil pan. So for the lubricant to work at an optimal level it needs to both support the loads to prevent metal contact and move a quickly through the system as possible to carry away heat. A thick viscosity lubricant in a tight tolerance engine limits it's ability move through an engine quickly and reduces it's effectiveness. High oil pressure readings are not necessarily a good thing.

The oil also serves the purpose of removing heat. When you run excess oil pressure you are adding heat to the oil. Loose fitting bearings run high volume pumps to move the most amount of oil in a given time. These bearings will not stand up to longevity but will tolerate high rpms for the duration of the race. It's a tradeoff.

[Fred A]

Changing oil often is most important. Good Luck with the rest: Fred A

[Ol' Ron]

Yes, Jseery you hit the nail on the head. In theory, the stock engine clearances could handle 5-20. The original bearing clearances would call for that. Unfortunately the flathead routes the oil through the cam, and if that isn't tight you could loose allot of oil.
BTW, you builders, check the cam bearigs that are coming out. I'm told they are very loose .006" Sometimes you don't have to change them.

[rotorwrench]

A lot of the low viscosity motor oils started to show up when higher fuel mileage became mandated by government regulations. The low viscosity stuff like SAE 5W/20 has less windage and allows the engine to operate with a little bit less friction. This translates into marginally better fuel mileage but over a longer period, it adds up. The auto manufacturers are using every advantage they can get to keep passing the regulatory standards these days. Eventually we will have to go to electric cars or at least hybrids with small engines to charge the big batteries.