i am interested in running a mobil 1 oil in my 350 tpi...i have always use just regular old mobil since i have owned the 87 camaro...the car has 87000 on it i have put 18000 of my own miles on it. the reason for the quesion is that i have heard that mobil 1 has such great cleaning power it may knock dirt loose in the engine and damage it...i have also heard that it may then start to burn oil....are these storys just that or are these things true????

 

As usual, there's a mixture of fact and myth there.

In 1971 when AMSOIL introduced the first automotive synthetic, petroleum-based lubes, especially multi-grade types, would deposit copious amounts of sludge and varnish inside an engine. In the decades since, and especially because of the superior detergent capabilities exhibited by synthetics, API and the manufacturers have required better properties from all API-approved engine lubes. So, the problem isn't as bad as it used to be, but there are some things to consider.

If the engine has been well maintained with petroleum oil, it won't have too bad of deposits in it. You can get an idea how bad it is by looking under the oil fill cap and looking at the rockers/springs underneath. If you see substantial build-up, you may want to go through a "cleansing" process before you switch over. Otherwise, you can just switch over and keep an eye on the appearance of the oil on the dipstick - if it gets black really quickly, as in quicker than it does with a petroleum oil change, just change the synthetic again along with the filter.

3 "cleansing" methods of which I know:

1) ATF method: Change the oil with petroleum, but use one quart of ATF in place of one quart of oil. Run for 500-1000 miles, change to synthetic. I've never done it, I don't much like the idea of putting an oil in there that isn't intended to be a motor oil, but lots of people do it. The ATF has more of a detergent property to it than the typical engine oil does.

2) Slow conversion method: Change the oil with petroleum, but use one quart of synthetic in place of one quart of oil (4 to 1). Run for the normal oil change interval. At the next oil change, use 3 quarts petroleum, 2 quarts synthetic. Next change, 2 quarts petroleum & 3 quarts synthetic, etc., until the entire change is synthetic. Of course, change the filter with each oil change. This will slowly clean out the petroleum lube breakdown products.

3) Flush: AMSOIL makes a great flush that they developed in the 80's when petroleum deposits were worse than they are now. Before the oil change, add the flush and run at high idle for 30 minutes (w/o driving the car). Drain, change filter, fill with synthetic. When I've switched older engines over using this product, I halved the oil change interval, used the flush at the next change, and then went with the full synthetic oil change interval.

I've been using AMSOIL since 1983. The only issues I've seen are: 1) Petroleum oil deposits under the intake manifold splash shield and around the exhaust cross-over passages are very difficult to flush out. Almost always have to mechanically clean them for best effect. 2) SBC valve stem seals will harden with time when using petroleum oil. Almost always need to be replaced in order to reduce oil consumption, but it's no worse than it was with petroleum oil. 3) Mobil 1 tends to leak past seals more than AMSOIL, but some of M1's later formulations are better about that. 4) I've seen a grand total of one engine that had deposits so bad that they ended up plugging the oil pump pickup screen after being switched over to synthetic. That car had been owned by "trailer trash" that neglected it horribly, and the trailer park had been flooded while the car was parked there. My dad "rescued" it from the junk yard. It was on its 2nd AMSOIL change when the screen finally plugged. We'll never know if it would have failed if Dad's oil changes had been petroleum, but I suspect it would have.