confused about engine oil

Forum members, my Unique has a 351 Cleveland. The engine has about 19k miles on it since it was rebuilt. The previous owner used Rotella T synthetic exclusively and cited a need for high zinc content for the flat tappet design. Apparently this oil is designed for heavy duty engines (i.e. truck). I have heard the need for high amounts of zinc in the oil for break-in for flat tappets and not necessary after that. I have also heard that running synthetic in a "vintage" engine (circa 1971) may promote leaks as opposed to a non-syntetic oil. I want to put the "right" oil in this engine to keep it running properly and would appreciate any feedback on what is "right" for a Cleveland 351 engine. Thanks, Chris

I am not claiming to have any knowledge about any particular oil and i certainly don't want to lead you in the wrong direction, but if you have 19,000 miles on your engine and no problems to date, I probably wouldn't change anything. The only thing i have to back this up is that we have a fleet of trucks and in the past have tried switching oils for one reason or another and in a lot of cases, switching oils caused some of the trucks to start burning oil. I guess some engines don't like changes???? I do know that we get an additional 100,000 miles in warrenty coverage from the manufacture on the trans and rears if we keep synthetic in them, so thats gotta say something good about synthetics.
This will scare you, but we have taken our trucks to 20,000 miles between oil changes and have the guarentee from the oil and filter supplier we won't have any problems. We send in oil samples for testing at each service and havent had a single problem in the past two years since going from 12,000 to 20,000 miles between oil changes. You can imagine the savings we have seen, especially when you consider each truck holds 10 - 12 gallons of oil and run 3-4,000 miles / week. Our engine oil is not a synthetic. The rotella you have been running was designed for trucks and heavy equipment and is an excellent oil in those applications, showing little or no bearing wear when we drop the pan from time to time. we have many trucks with well over a million miles on them. Everyone likes their particular flavor of oil for one reason or another, but if you have that many trouble free miles on your cleveland, I see no reason to switch to anything different. What weight is the rotella your running? Rotella is typicaly a thicker weight oil.
If you have any concerns, have an oil analysis done their very inexpensive.
Eddie

I've used synthetic and conventional oil in my stroker over the years. I've settled on Amsoil 15w50 racing synthetic for my engine. I like the idea that the synthetic starts lubricating immediatly, I'm sure much sooner than 50 weight conventional oil. Even in cold weather, I feel better about the Amsoil. I run a flat tappet cam and Amsoil has a high content of Zinc.

rotella t hasnt had the high zinc content in a couple years now. had something to do with DOT regs. changing. found that out a couple months back after talking to an edelbrock tech guy when my high lift flat tappet cam ate three lifters and lobes shortly after putting the new lower zinc rotella T. he said to get high zinc content you need racing oil. im using valvoline vr oil now. later brian

This discussion could go on forever, I ran Valvoline 20-50W Racing oil during break in with one quart of Marvel Mystery Oil (This stuff has been around forever). Then changed to synthetic, my engine leaked around the pan, the rear seal, and the remote oil filter adapter, and the valve covers.....maybe seeped is the correct word. Since I change oil every spring and only drive 1,000 - 1,500 miles a year I went back to Valvoline 20-50W Racing oil and my one quart of the Marvel Myster Oil, the leaking stopped. My dad was a big fan of Marvel Mystery oil, he had 50 years with the CAA, which later became the FAA, a Electro Mechanical Engineeer over Nav Aids. He used the Marvel Mystery oil as an additive in Diesel Fuel and engine oil in the diesel generators engines, back up systems for the Nav Aids if the power went out. Later on I became friends with Dale Pulde, NHRA Hall of Fame, Funny Car Driver, and Drag Racer, he told me they used Marvel Mystery Oil in the Funny Cars for years. So I use it in every engine I have broke in, Motorcycles, Diesels, ect. and then as aditive too.
Back to the subject, I see no reason to spend extra bucks for synthetic when I change every year, in my reasoning you must change every year. Even if the oil just sits in the engines there is chemical changes taking place, acids, bi-metal chemical changes, moisture, fuel, ect. So once a year the oil and filter get changed. Brian is correct the conventional diesel engine oils have changed and they are no longer what they use to be, high in zinc content however Valvoline Racing Oil is. I have a solid lifter engine....and that's the protection I need. I am sure there are other oils that have a good zinc content rating that would work good too. That's my take on the Cobra Oil.
One other note, I am an Amsoil fan and a dealer of their products, I use it in my Diesel Truck, Motorcycle, SUV, ATV, lawnmowers and their 2 cycle oil in chain saws, weed eaters, ect. very good stuff.[thumb]

Why will some oils allow an engine to leak, but others won't? Does it have something to do with swelling the gaskets or ?

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Originally Posted by eliminator

This discussion could go on forever, I ran Valvoline 20-50W Racing oil during break in with one quart of Marvel Mystery Oil (This stuff has been around forever). Then changed to synthetic, my engine leaked around the pan, the rear seal, and the remote oil filter adapter, and the valve covers.....maybe seeped is the correct word. Since I change oil every spring and only drive 1,000 - 1,500 miles a year I went back to Valvoline 20-50W Racing oil and my one quart of the Marvel Myster Oil, the leaking stopped. My dad was a big fan of Marvel Mystery oil, he had 50 years with the CAA, which later became the FAA, a Electro Mechanical Engineeer over Nav Aids. He used the Marvel Mystery oil as an additive in Diesel Fuel and engine oil in the diesel generators engines, back up systems for the Nav Aids if the power went out. Later on I became friends with Dale Pulde, NHRA Hall of Fame, Funny Car Driver, and Drag Racer, he told me they used Marvel Mystery Oil in the Funny Cars for years. So I use it in every engine I have broke in, Motorcycles, Diesels, ect. and then as aditive too.
Back to the subject, I see no reason to spend extra bucks for synthetic when I change every year, in my reasoning you must change every year. Even if the oil just sits in the engines there is chemical changes taking place, acids, bi-metal chemical changes, moisture, fuel, ect. So once a year the oil and filter get changed. Brian is correct the conventional diesel engine oils have changed and they are no longer what they use to be, high in zinc content however Valvoline Racing Oil is. I have a solid lifter engine....and that's the protection I need. I am sure there are other oils that have a good zinc content rating that would work good too. That's my take on the Cobra Oil.
One other note, I am an Amsoil fan and a dealer of their products, I use it in my Diesel Truck, Motorcycle, SUV, ATV, lawnmowers and their 2 cycle oil in chain saws, weed eaters, ect. very good stuff.[thumb]

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I just bought a case of Schaeffer oil was told by the distributor that it has high zinc content.
I was running Mobil 1 so the distributor said to stay with a synthetic after reading your post I may take it back as I am having seepage and replacing the valve cover gaskets and re-torquing the heads while I replace the intake. I had heard that synthetic oil might leak were regular oil would not.

synthetic will not cause any appreciable wear compared to conventional oils. using conventional oil and changing it after only a 1000 miles or one year is obviously better than extended intervals but the wear starts immediately compared to a synthetic oil. of course synthetics won't stop things from breaking but it will stop the wear.

Castrol 20w-50 Syntec full synthetic is formulated for older vehicles and muscle cars with more zinc content. Also Brad Pitt racing oils are said to have higher levels of zinc.

-Geary

I have a Southern Automotive stroked 427 sideoiler, 5 years old.
I once asked Bill Parham, at a Unique homecoming, why he recomends Valvoline Racing oil (20-50 or straight 50). His reply was that sythetics, although good lubrication properties, have the downside of eating/emulsifying older gasket materials. Here's the leak issue. Antifoaming and high zinc is also important.
For my way of thinking, run what the engine builder says, don't get creative here.
Just my 2 cents.