I have this thing for the '62 Biscayne's. I really like the cars. I think they are one of the best examples of the muscle car era with their 409's. I bring this up because the last 2 1962 Chevrolet Biscayne's I bought never had a oil filter on them. In 1962, the oil filter, as well as seat belts, were options. They both had the 235 inline 6cyl. with the 3 on the tree. One I used as a driver and the other, the one I drove all the way to New Mexico to get since it had zero rust, I've spent much more than I care to count, and have transplanted a 502ci big block in. With the driver one, I ran straight 30 weight, as cheap as I could find, oil in it and changed the oil every 3000 miles. When I sold it, it had 185,000 miles on it and sounded like a well oiled sewing machine when running. It never smoked, used oil, and seemed like it would simply run forever. As far as I know, it's still running.
The 6 cyl. I took out of the one I've made into a hot rod show car has 61,000 original miles on it and it started and ran flawlessly when I pulled it. I carefully filled it with fresh oil, put Stabil in the fuel, ran it for 5 minutes and shut it off. I then pulled the engine and transmission and strapped it to a crate and it still sits on a shelf right over my work bench in my shop just waiting for me to find the "perfect" '62 to buy that needs an engine and transmission.
I did pull the oil pan off of it and the valve cover off of it before I stored it. No sludge, no blackening, no varnish, no discoloring etc. It appeared to show no wear at all. How can that happen when it never had an oil filter on it and it had never seen synthetic oil?
I'm a believer in synthetic oil and think (no, I know) that in some engines like the Chrysler 2.7 liter, it is all but mandatory. If you have a Chrysler 2.7 liter engine and run 6 months and 7500 miles between changes with regular "dino" oil, it will begin sludging around 25K miles, it will develop moderate sludge around 50K miles with some engines beginning to fail, and by 75K miles they will be basically a ticking time bomb waiting to blow due to lack of lubrication as a direct result of sludge blocking oil passages. Do a search on this engine on Google, you will likely find thousands of cases that follow the pattern I just laid out.
Now the kicker, out of thousands of the 2.7 liter failures, I'm not aware of any that have failed where the owner had always used synthetic oil and changed their oil on a regular (and realistic) basis. One of my employees has a 2.7 that currently has 176,000 miles on it and is still running strong. He has always used synthetic in it since he bought it with 25k miles on it.
Soooo, that also brings up another issue. When doing an "engine flush" with older engines and switching to synthetic there is yet another cavaet. The engine has a relatively small oil pickup screen that can easily be plugged with the sludge that is broken loose by the flush. Even the best synthetic oil doesn't do much good if it does not circulate through the engine. No oil circulation = expensive noise.
There are other engines like the 2.7 Chrysler, so it is not an isolated case. If you have a Cadillac Catera, best case would be to sell it. /forums/images/graemlins/blush.gif It suffers the same problem as the 2.7 just discussed, but Opel, the engine maker, isn't any longer on good terms with GM. Therefore, when it goes, there is a real parts issue. Well, I'm completely off of tractors, but I'd suppose some of the same issues would apply.
So, the answer to whether synthetic oil is good for older engines....looks like a definite "maybe". /forums/images/graemlins/confused.gif
