1940 248 engine - modern engine oil?

I've done some searching but haven't been able to find any solid information about modern engine oils for the 248. My research has indicated that 20W was original spec, which is not the easiest oil to source in 2014. Has there been success with modern multi-grade oils in these engines? With the necessary ZDDP additive, of course (unless running one of the hot-rod oil brands).

You're going to get a lot of debate on this one! If you search this forum you will find many threads discussing this very issue. Lots of opinions - multi-vis vs single grade, detergent vs non, etc. Remember that the 20W as spec'd in the manual is nowhere near the same as 20W today. Do you have a filter? If not, stick with a non-detergent like Shell Rotella. I use a multi-vis myself, but others like single grade.

Am now letting the fur fly...

Cheers, Dave

You're going to get a lot of debate on this one! If you search this forum you will find many threads discussing this very issue.

I did a bunch of searching on here (first rule of online forums ), but didn't seem to turn up very much regarding the 248 in particular. I know there are many schools of thought on oil brands/viscosity!

Do you have a filter? If not, stick with a non-detergent like Shell Rotella. I use a multi-vis myself, but others like single grade.

Yes, my 248 has an oil filter.

RyPow

Any oil you can buy today is better than the BEST oil in the '40s. I use Rotella 10w 30 in mine.

Ben

RyPow

Any oil you can buy today is better than the BEST oil in the '40s. I use Rotella 10w 30 in mine.

Ben

I believe that. I'm just treading lightly and want to do my homework before touching this engine as I haven't dealt with anything older than 1968 before.

I don't know of any particular issue with the 248 itself. All discussion I have seen is for the entire family of late 30s - late 40s engines, so I think you can safely apply them to your situation.

Even with the filter some will say to stick with non-detergent since the filter throughput is a fraction of pump output. But if you change it often it may not make any difference.

Cheers, Dave

An important consideration is the history of the car and engine. Is it original untouched, has it been rebuilt fairly recently and such.

If it is has been recently rebuilt, then any good 20-40 oil would be fine.

If it is an old or original engine, the first thing I would do is drop the pan and see what is "living" there. Clean the pan, check the pump and then refill with a non-detergent oil.

If you have any doubts or concerns, you should definitely drop the pan. Messy, but not hard nor expensive. Probably the cheapest engine insurance you can get.

As has been already mentioned- anything you get today is better than what it had when it was new.

I agree with Don. Since my 41 248 is not rebuilt I use non-detergent 30W. If it were rebuilt, I would use something more modern. I have owned and driven the car without issues for 10 years.

An important consideration is the history of the car and engine. Is it original untouched, has it been rebuilt fairly recently and such.

If it is has been recently rebuilt, then any good 20-40 oil would be fine.

If it is an old or original engine, the first thing I would do is drop the pan and see what is "living" there. Clean the pan, check the pump and then refill with a non-detergent oil.

If you have any doubts or concerns, you should definitely drop the pan. Messy, but not hard nor expensive. Probably the cheapest engine insurance you can get.

As has been already mentioned- anything you get today is better than what it had when it was new.

Okay so I'm new at this GM/Buick scene but what's being said here sounds very much same as discussions I've had on Ford forums. I have a '56 Fairlane with Yblock and was advised to run 15W40 oil, with about 4 oz of Lucas Engine Breakin Additive added, to assure adequate zinc is in the oil. Now the Ford has flat tappets and supposedly the zinc is helpful for lubrication of the tappets/cam lobes. I recently got a '41 Super with the 248 combo carb setup, hasn't been running in awhile but I hope to get her going soon. It appears to be low mileage (under 35K) and PO said it ran fine when he put it in storage a few years ago.

I'm inclined to think the same oil/additive combination for this engine as my Ford would be a good one. Any advice? Thanks!

Just my two cents worth - I use Rotella 15w-40, and have had no problems. No filter, I change every 1000 miles. It gets pretty hot here in central Florida, and the oil pressure is adequate. This engine was rebuilt 35,000 miles ago, and is still going strong. Yes, I add ZDDP with each change.

Gary

Raceron I would agree with Den41Buick and DonMitcheletti advice above on the 41 Super and run non detergent oil. Detergent oil was probably run in your 1956 since it was new. On the other hand your 41 ran non detergent most if not all of it's life and by switching you run the risk of cleaning out crud from places that your engine has been storing it for many years. Thereby creating headaches.

Personally I run non detergent oil in everything that does not have a full flow filter. Detergent oil is designed to pick up debris and carry it to the filter where it is soon removed. Without a full flow filter it just keeps carrying the debris. Do you really want all the crud that is picked up by detergent oil continually running over bearing surfaces without being filtered?

Keep in mind that the large oil pans in older cars work as settling basins for particulates and were the only "filter" for the original oil system (so, seeing sludge in your pan is not necessarily a bad thing). Using modern oil with "detergents" (suspension additives) can be detrimental to original un-restored engines as described above.

If your engine has been rebuilt and fitted with a full flow oil filter, you can use just about any oil you want. Even a partial flow filter will eventually filter all the oil in the system. Meanwhile, that big oil pan will still work to drop out the heavier solids that the partial filter may miss. So, even with partial filters on my cars, I still use "non-detergent" oils to allow the oil pan to do it's job.

Multi-viscosity oils allow your engine to start cold and run hot while maintaining proper oil pressure without changing oil for summer and winter driving. So I use 20W-40 in most of my cars.

Just my $0.02

My '56 Ford 312 Yblock had a complete engine rebuild so the 15W40 detergent oil & Lucas additive is what I will stick with in it. But the Buick hasn't been rebuilt that I know of and has no filter. So along with what y'all are saying here and what I've heard & read elsewhere, advice is to go with a straight weight non-detergent oil & the Lucas additive, and just keep it changed every 1000 miles or so. thanks for the input