Need oil recommendation, vintage engine...

[3onthetree47]

Hello everyone!
I'm new to the forum and this is my first post. I own a 1947 Buick Special 4 dr sedan with the original Buick Fire Ball ohv 248 ci straight eight. It has babbit rod bearings and cam bearings. No oil filter (from factory) .
I had the valve train rebuilt with new springs, valves, guides, rebuilt oil pump and the cylinders re-rung with standard rings. The rebuilder put in 10w-30. It runs with 112 lbs in ea. Cylinder (6.5:1), 30 lbs oil pressure at 500 rpm hot idle, 42 lbs at speed...all are factory spec. The engine does still leak a little from the rear main seal, and I do see some blow-by in the valve cover. Nothing in the draft tube (pre-PCV) or exhaust and my AC 48 (NOS) standard plugs look good.
Factory calls for 20w oil down to 32* ( no degree symbol on I-pad [censored]?) below that temp it recommends to substitute 10% kerosene! So what do you recommend?
0-20?, 5-20?, 5-30? Stay with 10-30? I do add zddp to my oil as it has flat tappets. I read lots on this forum but could not find anything specific. Any one out there familiar with vintage iron? Thanks, and sorry for the long post.
-3onthetree47

 

[zrxkawboy]

Welcome! Personally I'd use 10W30, either a HM oil (Maxlife, etc) or a HDEO (Rotella,etc).

 

[CarbonSteel]

to BITOG!

I would use Rotella or any good HDEO in it. Love hearing about these old classics that are still around!

 

[Rolla07]

Originally Posted By: zrxkawboy
Welcome! Personally I'd use 10W30, either a HM oil (Maxlife, etc) or a HDEO (Rotella,etc).


+1

 

[Chris142]

Any decient oil such as 5w30 or 10w30 will have more ZDDP than that engine was designed for. When that was new oils were Non Detergent with few or no Anti wear addatives.

Personally I like 10w30.

 

[eagle23]

+1 on Rotella; it's stout stuff for those older engines. 10-30 should be good given your good oil pressure readings.

Any pix you can share with us?

 

[mechtech2]

I'd use 5-30. [Forget the 20 and adding 10% kerosene or gasoline.]

And after break in, those weak valvetrains need no extra ZDDP.
I also would have milled the head to get 7to1 compression.

 

[CATERHAM]

Originally Posted By: mechtech2
I'd use 5-30. [Forget the 20 and adding 10% kerosene or gasoline.]
And after break in, those weak valvetrains need no extra ZDDP.
I also would have milled the head to get 7to1 compression.

+1. Yes run any 5W-30.

And Welcome to BITOG!

 

[SS1970chrysler]

Welcome to another old car lover!

I would also recommend 10w-30 Rotella or even a HM version if available. I use it in my 48 Packard whenever I find it. it doesn't have an oil filter either.
Rotella, I could run all year or use cheap 10w-30 and change more often.

 

[vintageant]

+1 Welcome to another old car lover!

Have a good read of these two separate opinions for older engines:

http://www.lnengineering.com/oil.html

http://www.widman.biz/uploads/Corvair_oil.pdf

 

[A_Harman]

Is there a way you can put an oil filter on it? That would be my first suggestion. The oil itself is not so critical, since you're already dosing it with zddp. Any name-brand SN conventional 10w30 today is better than any SB oil from 1947.

How much do you drive it? Does it stay in the garage until spring, and then only come out when the day is guaranteed to be sunny and above 60F?

 

[SS1970chrysler]

I'd like to add that you really should drop and clean out the oil pan and pickup. Those vehicles without filters used mostly ND oil which was intended to trap contaminants in the sludge at bottom of the pan. I slowly transitioned to detergent oil by substituting one more qt each time until most of the gunk was gone.

 

[afoulk]

just out of curiosity, how long did the factories recommend running oil in engines like this without the filter before it was time to change it again?

 

[wolfc70]

Originally Posted By: afoulk
just out of curiosity, how long did the factories recommend running oil in engines like this without the filter before it was time to change it again?


500 miles to 1000 miles depending on application. Kendall was one of the first to tout a 2000 mile OCI. Hence the two fingers on the logo.

This I got from stories of my grandparents, and friends grandparents. That and I saw a owners manual for a 1941 Mercedes w136 once. It called for 20w-20 oil and below 10F to thin the oil with kerosene and short (500 miles) OCI for winter use. It also called for de-coking the cylinder head every 5000 miles. At some mileage point it told you to disassemble the entire car! Even as a kid it seemed very maintenance intensive.

 

[OilProfessor]

The Professor recommends Quaker State 10W-30.

 

[vintageant]

The Instruction Book of my 1937 Alvis states:

"At intervals of 1,500 to 2,000 miles, it is desirable to completely drain the oil sump and clean the filter before filling up with fresh oil."

The filter is a detachable circular gauze strainer

 

[3onthetree47]

Thanks everyone for the welcome and recommendations. I have looked into adding the factory filter setup that many of these Buicks had. The problem is finding one. When installed, it filters the oil going to the head only. I drive this car all year and avoid rain salted roads...o.k. And the bitter cold when no one else in their right mind is driving their classic. The oil change interval is 3k in the manual, but I have been changing it every four months. I did drop the pan before the rebuild, cleaned out the gunk in the pan and cleaned the oil pump pickup. Sorry that my responses are out of order to the replies. I cannot figure out how to attach pics.
3onthetree

 

[SS1970chrysler]

oil filters at the time were a "partial-flow' system and you can adapt one from almost any car from the period. Many people did this back then. I believe I still have a filter system from an old studebaker around here somewhere.
The partial flow system does reduce oil psi a little bit, but does filter all the oil within 10-15 minutes of operation.
That's great to hear you've already done those things to your Buick and I hope it serves you well.

 

[A_Harman]

Wow, you drive it year-round. 6 or 12 Volt electrical system? I can't remember when they went to 12-volt. If 6-volt, then definitely a 5w30 SN oil along with the zddp additive. Those 6-volt systems always cranked the engines so slowly, I was never confident that they would start.

 

[mechtech2]

BTW, I am loosely affiliated with a '38 Buick. I am surprised in 1947 they still use the old oil specs and esp the kerosene trick in the winter.