I would like to get some opions about regular oil vs synthetic.

Is it a matter of choice? What are the pros and cons? I know sythentic cost about 3x as much so I was just wondering.

Also, does it hurt much to switch between the 2?

I know last time I went I got reg instead of synthetic.


Also what about gas. The manual says out of the 3 gases 91,89,87 octane. It says to use only 91 the premium stuff but gezz the way gas prices have been lately I have been using 89. That isn't going to damage anything will it?

Probally 2 stupid questions but hey everything is open for debate.

Synthetic VS Regular Oil?
91 Octane VS 89 Octane?

 

hhmmm... you don't have to wait 3,000 to 5,000 miles to answer

 

More than dino oil versus synthetic oil, what is more important, I feel, is using the right viscosity of oil for the driving conditions and style, and ambient temperatures. I use 5W30 or 0W30 in the winter, and 5W50 and 10W40 in the summer.

dino:
pros: cheap, lasts the same miles.
cons: always wonder if syn would be better

syn:
pros: makes you feel good, get about 3 hp gain if you use syn 0W30 over dino 10W40. (Tests performed by Castrol and Williams F1 Team)
cons: expensive

higher viscosity oil (thicker) protects better at higher temps, and for older mileage vehicles. Lower visc is better for initial lubrication, and better gas mileage. The wider the range (5-50) the more the oil is prone to viscosity breakdown at high temps and long terms, compared to 5-30 which is more stable.

Of course, you can mix and match oils and brands to create custom blends to get the right balance of price to performance. It'll certainly make you feel smarter.

Use 91 or 93 octane, that is what your LS400 was designed to use. Nothing else. 89 will do in a bind, but add 93 immediately at the next pump. 89 will not damage engine in the short run, but it will damage engine if used for several years. You can also blend 93 + 89 to get 91 if cost is a concern. But it may not be worth the hassle. Simply put, if you cannot afford high octane gas, do not buy high performance machines. Think before you buy.

Also consider using ethyl alcohol fuels (or blends) in the winter. Ethanol, is a common soluent in gas and water, and help remove condensation from the petrol by dissolving the water in the gas. Never use methyl alcohol or additives containing it, as it is corrosive.

I hope that helps