Dear AMSOIL,

I thought you might appreciate hearing my AMSOIL story.

When the opportunity arose last year to purchase my mother-in-law's 1987 Cadillac DeVille, I jumped at the chance. A true low mileage survivor, it was in near pristine condition. I was proudly showing it off to a mechanic friend when he said, "Uh-oh, you bought an HT-4100? Good luck buddy."

After much research I understood what he meant. The HT-4100 was rumored to be one of the most troublesome engines Cadillac ever built. The problems are numerous: an aluminum block with cast iron heads that expand and contract at different rates causing premature head and intake gasket failure, coolant loss into the oil, and finally main and rod bearing failure. They also have a heavily loaded distributor gear, weak timing gears, and sludging issues.

My first thought was, if ever an engine needed AMSOIL, it's this one. I first heard about AMSOIL at the old Brohman Dragway in the late 1970s from a fellow racer who swore by it. For the past 10 years, I've used various synthetic oils with favorable results, but never AMSOIL. Then I talked with Dave Mann, the AMSOIL Dealer in my home town, and told him my story. Having spent 19 years as a lubrication specialist with Ford, Dave knows his stuff. He made several recommendations, and shared with me his excellent e-book on motor oils.

I also asked around at the Cadillac owners group I belong to, and almost every one of them said, "Don't buy AMSOIL! It's too expensive and won't do you any good. You need this or that oil with this or that additive," and so on.

So who was I to believe?

Having spent over 25 years in advertising and marketing, I have a strong skepticism for extravagant claims made by manufacturers. Usually, when you hear impressive adjectives like "advanced" and "superior," someone just wants your money or your vote (or both). So I read the science; from AMSOIL and from several independent studies. I came to the conclusion that it really is an excellent product. It also intrigued me that one of the primary sales points made by AMSOIL is to convince you to buy LESS of their product. That kind of marketing is contrary to anything I've experienced, and elevates AMSOIL's credibility level exponentially.

I switched the Cadillac over to AMSOIL 5W-30 (ASL) last fall, then put in AMSOIL 10W-30 (ATM) this spring (even though it's not a turbo, I like the extra wear protection offered by this formula). Rather than letting the oil go a full year, I change it every six months, during which time it accumulates about 6,000 miles. My dad was an auto mechanic and taught the 3,000-mile oil change rule like it was the 11th commandment - that kind of conditioning is hard to overcome. With this frequency, I still spend less money than if I changed the oil on a three-month/3,000-mile schedule. I use the money I save to have drain samples tested by an independent lab each time.

The Deville now has 50,000 miles and runs like a fine Swiss watch. I have not had a single problem with the 'troublesome' HT-4100 engine. It runs roughly 10 degrees cooler than with regular oil, and my gas mileage has increased by 10%. It has become my mission to get 200,000 miles from this car. With AMSOIL, I might just make it.

As an addendum, I also recently switched my wife's 2003 Oldsmobile Silhouette minivan to AMSOIL. Since we've owned it, this car has had a lifter clatter for the first 10 seconds on cold starts. Literally, on the first start after putting in AMSOIL, the clatter was gone.

Thanks AMSOIL. By making a superb product that truly does what you say it will do, you've given new life to a sweet old Cadillac, and made a believer out of this devout skeptic.

Steve Cook
Traverse City, Michigan