Well, I am for synthetic for a couple of reasons. One, I have logged about a 750,000 on it in gassers. First car sold at 345,000 miles and is still running (83 Chevy Celebrity 2.8), second, Chevy S10 2.5 liter given to family member with 274,000 (currently not running, radiator leak, ran with no coolant for over 20 miles, cracked cylinder head but remainder of engine checked out fine), last car sold at 174,000 and still running and current vehicle with about 60,000 on the clock and of course still running. This is not to mention the "other" vehicles I have running it, parents cars, sisters cars etc.
When working in the machine shop, we did many state patrol vehicles which are put on synthetic following a short break in period. We worked on Chevy and Ford Modulars and saw next to NO wear in these engines after 200,000 or so miles. We mostly cleaned them up, got them ready for reassembly and such after checking everything out, and they went out to be re-assembled. Kind of like major preventative maintenence. They were reassembled with new rings and gaskets, ran on dino for the first 3,000 miles and then again switched to synthetic.
I run 10,000 miles on a quality filter and then change the whole works. Money wise it is cheaper to run synthetic, but quality wise, I think the longevity of my vehicles speaks for that. I have NEVER experienced any leakage problems and such as other have reported. I will say if you have an oil leak prior to adding synthetic, you will have a worse one after adding it, but I attribute that to synthetics ability to flow better anyway.
My uncle switched to synthetic and lost an oil seal. He did it on a vehicle that had over 100,000 miles on it with dino. He swears synthetic did it and has pointed me to several articles showing similar results. Personally, I have not had those problems. I did have to replace the timing gear in my Celebrity after about 224,000 miles as the nylon gear gave up the ghost. The inside of the engine was absolutely clean, had a bronze color to it and was well within tolerance on cylinder and cam lift measurements.
Just my .02 and yes, once the oil leaks on my 6.9 have been stopped, head gaskets replaced or other motor transplanted, it will get synthetic. At this point, I don't care to watch it run out as fast as I pour it in!
On edit: I use Wix filters, I purchase them from
www.filter1.com, regardless of what type of oil I use. Yes, they are a little more money but a good filter. When considering my oil change costs, I change dino every 3,000 miles, synthetic every 10,000 miles. So in the same mileage window, for dino I am using 3 1/3 filters, plus the same in oil. In synthetic, I am using 1 filter and one change of oil. I buy Syntec at 18.00 per 5 quart container, dino costs about $6.00 for same. So, in essence, I am saving about $2.00 on oil in the 10,000 mile run and the cost of 2 1/3 filters!
