Good idea or not? My '98 has about 110,000 on it, and has had conventional oil in it in the five years I've had it. Most of the internal engine gaskets and seals were updated at about 76,000 miles due a intake gasket leak repair. It has no oil leaks or problems at this time. I want to switch it over to synthetic. Can I just drain the old and fill with synthetic? A parts guy at my local store recommended I use Gunk "engine flush" before I switch over. I have never been a big fan of products like this. Is this safe for my motor? What does everyone recommend???

 

Why change what's worked for all those miles?

 

I am considering a synthetic switch for mileage. See if it works.

 

Nah, I don't think I'd worry about it unless you're the experimental type.

 

I wouldn't suggest going to a PAO synthetic with the miles you have on your engine. While the PAO doesn't present a problem, the ester used to mix and hold the additive package will have a cleansing effect and the sludge and varnish at the seals will probably be dissolved resulting in a leak. There is no more lubricity in a synthetic so more fuel mileage is more myth than anything. Synthetics usually run to the thinner side of the viscosity range and may have some mileage benefits but the same thing can be achieved by using an Energy Conserving rated dino oil. I don't think switching now would be a wise decision.
The benefits of a synthetic are extreme cold flow properties at startup and longer oil change intervals. Most anything else is urban legend. They are not slicker, won't make your engine go one mile further under normal driving conditions, and with todays dino technology- aren't much of advantage in extreme heat. If you want to use them on a newer, lower mileage engine- it's your engine and your money.

 

Well, you may have talked me out of it. If there isn't any big mileage benefit, it may not be worth the extra money. Thanks for your input.