Using synthetic oil

Bret86844 said:

Synthetic oil is great stuff. It's my understanding the oil itself lasts a very long time and really it's the filter that ends up needing changed first.

A lot of cars that come from the factory with synthetic have recommended maintenance intervals of 10,000 miles or more.

Click to expand...

While you can run longer intervals on synthetics if the base numbers and additive packages are correct, the filtration of the oil isn't the limiting factor in many cases.

AMSoil does sell a remote dual filtration unit that keeps the oil darn near clean, but the additive and base numbers are what typically create the necessity to change the oil in a car.

gregzoll said:

That is actually false. Synthetic blends allow an engine to be able to not burn off the oil at high temps. It has nothing to do with how fast oil leaks if a seal goes.

Japan and Germany perfected the use of Synthetic Oils during WWII. Over time, Synthetic blends have gotten better, that they are now able to save on how much recycled conventional oil and refined crude's for oils.

Click to expand...

Synthetic oils do, on average, have higher TFout numbers which limits their burn off and volatilization, however, I was speaking more to leaks at rubber seals and other gasket surfaces and not any consumable aspect of the oil.

Synthetic oils are usually both slipperier and smaller. If you have a seal (assuming that it is a post 1992 motor with seals that are rated for use with synthetics) that is leaking with a dino oil, it will leak faster with synthetic.

http://www.cenex.com/about/cenex-in...page/oil-and-lubricants/five-engine-oil-myths

This is an often-cited myth. In fact, if your seals and gaskets are in good condition, synthetic oil will not leak in your engine. Synthetic oil has not been shown to deteriorate engine seals or gaskets. But it might find an existing leak. The smaller molecules of synthetic oil are able to pass through very small cracks and crevices that the larger molecules of petroleum-based oil cannot. Eventually, those small cracks and crevices can lead to bigger problems — with or without synthetic oil.

http://www.aircooled.net/synthetic-vw-oil/
Synthetic oil causing oil leaks is another commonly spread myth. The truth of the matter is that if all your engine seals and gaskets are in good condition, synthetic oil will NOT leak in your engine. The myth started because on occasion, an engine will leak with synthetic oil, but not dino oil. The reason for this is that the smaller molecules of the synthetic are able to get past very small crevices, where the larger molecules of dino oil cannot. But this does not mean that the synthetic oil has caused the leak, it simply has “discovered” an infant leak, and regardless of what oil you are running, this infant leak will eventually grow to a size that will allow dino oil to occupy and pass also. Synthetic oil has not been shown to deteriorate engine seals or gaskets. It is not some evil solvent that will break down sealant, or anything like that. Like was said earlier, it is just a man-made base stock, that is uniform and smaller in molecule size than dino oil. Nothing more, nothing less.
I have seen cars that showed no signs of leakage start leaking with synthetic oils. Now, this could be a function of several things that all existed prior to the synthetic oils, but the combination of the smaller and more slippery molecule can manifest as a leak.

Synthetics tend to have a better additive package as well and I have seen motors that were previously run on conventional oil get "cleaned" by the higher end synthetic. In doing so, it scrubbed out some of the sludge that was previously band-aiding the seal that now started to leak.

Again...none of these things are the fault of the synthetic oil and I still run them in every single one of my cars, but the potential for a more significant leak where one already exists is definitely there with synthetic oils.

Very reasonable trade off in my opinion based on the better performance.