Oil Viscosity question

Flathead

Flathead

Well-known member
My engine is tired. How thick can I go on the oil (warm weather operation) and still have it flow down the tubes to lube the main bearings etc. The engine is not full of sludge, I have had the oil pan and side cover off already. I would like to get a little more use out of it while I finish rebuilding another to replace it. Interested in other people's experiences. Thanks.
 
I am running 10-40 in my Model T. The inside oil line is about 1/4 ID. the oils a bit stiff when cold but get to the front.
 
I used non-detergent 50 in my old and worn-out-engine for summer operation
No filter; New oil every 800miles.

As requested, I do use 10 W40 with my actual engine all around the year
With filter and one change each year (about every 6000 miles)

Have fun
"Tired" does not mean it is going to fail soon....
Dont push and it will go lots of additional miles.
 
My old Plymouth had a worn out flathead-6 that needed a quart of 40- weight every 60 miles. For summer use, I found an aircraft 60-weight oil and was able to go 100 miles on a quart.
 
If you go too high, you'll loose any cold start protection.

Get the lowest first number you can, with the second number just high enough to lower the oil consumption. 15W-40 or 20W-50 if it burns a lot (I don't think 50 comes with a lower W rating, unfortunetly)

Going really thick will wear it faster, as there won't be enough flow. Any high viscosity straight weights won't have much flow when cold.
 
If you really want to go extreme, use 0W-50 synthetic. Polaris sells it for atv use...
 
I use Walmart brand 20w50. It works good for me in all of my model A engines. Zinc sure doesn't hurt but isn't necessary in engines with a forged camshaft. Model A's have a forged cam.
 
eagle said:
If you really want to go extreme, use 0W-50 synthetic. Polaris sells it for atv use...
Click to expand...

I have always heard with the older engines you shouldn't use synthetic because it will blow threw the seals easier then standard oil. Tell me if I am wrong.
 
I use a straight 40 wt detergent oil, along with a qt of lucas engine oil supp. have used this for 12 yrs. have taken oil samples in for testing and all the copper and aluim. content has dropped @30 percent or more from the first couple of years that I didn't use it ,I only drive the 50 ford from april to oct. I put on @ 1500 miles a year, best combo I ever used
 
Thanks for all the great replies. I think I will try some 20w50, I have had success with it in worn but pressure lubricated engines. I was curious about the A engine since the oil is not forced to the bearings by the pump but relies on gravity for the mains.
 
Mr_Coupe said:
I have always heard with the older engines you shouldn't use synthetic because it will blow threw the seals easier then standard oil. Tell me if I am wrong.
Click to expand...
Do not agree!! Synthetic and regular oil are the same when new,the only difference is synthetic oil will never break down. The additives in both oils will break down but the base in which the oils are made of are different. As far as weight or grade all oil at 212 degrees flow the same. I use 5-30 Castrol syntec in my 8BA. No leaks!! Some seepage at rear of pan but no oil drops!! Good Reading!! Pete
http://www.bobistheoilguy.com/motor-oil-101/
 
Mr_Coupe said:
I have always heard with the older engines you shouldn't use synthetic because it will blow threw the seals easier then standard oil. Tell me if I am wrong.
Click to expand...

Don't agree.

synthetic oil of any weight is the same viscosity as conventional oil, it would have no reason to 'blow threw seals".

Just as 0W40 is the same viscosity hot as 10w40, it simply doesn't get as thick as it cools which is beneficial to any engine out there.
 
Last thing I would worry about is the oil "blowing through the seals." There aren't any-at least as we know them in modern engines.
 
You must log in or register to reply here.
Back
Top