synthetic oil?

Synthetic oil usually 'looks' bad because it does a superior job of keeping 'varnish' dissolved/suspended. I have no idea if anyone has determined that the varnich left on engine internals is harmful, but synth. oil can dissolve it. It would look particularly bad from a vehicle that had been using convetnional oils and/or with extended drain intervals.

I doubt there would be any problem switching back.

Folks who fly planes or are responsible for fleet maintenance perform regular OA (oil analysis). Several companies can do this for individual's cars.

for more than you ever wanted to learn about engine oils, checkout

Carl

As an aside, my dealer uses Castrol part-synthetic for oil changes. The mechanic told me (unofficially, of course) that it's safe for at least

Synth is probably best for temperature extremes. If you change the oil & filter as per the vehicle's maintenance schedule (with either synth or dino), you can't go wrong. Just don't skimp on the filter.

snipped-for-privacy@gmail.com wrote in news: snipped-for-privacy@a5g2000pre.googlegroups.com:

Fully expected. Synth is only an advantage in extreme heat or extreme cold. It does not thicken as much cold, or thin/break down/ sludge in high temperatures.

My PT cruiser has a pretty tight hood area so I run synth to give the engine a fighting chance in the heat - and it doesn't hurt in the ontario winter cold either. I still change it every 4 months ot 6000km

"Dirty looking" doesn't really count. I've been around oil sampling by wurk's fleet services and have seen almost-black oil that tests fine for anything that would damage the engine.

Hi, Today's oil is far advanced compared to years passed by. synth oil every 6000km? You must have lots of money to waste. Is your car turblo charged one? Even regular 5W-30 will last 10k Km in normal driving. Do you replace spark plugs every 6 months too?, LOL!

Tony Hwang wrote in news:ImJSl.136818$ew.131479 @newsfe24.iad:

benefits?

If you don't change fluids as per the OEM schedule and the vehicle is under warranty, you may jeopardize your warranty.

istheoilguy.com

It all depends on how the car was driven ? Is that city miles or highway? or a combination.

If its city miles with few highway miles , its not the colour of the oil that will determine the oil change interval , but the accumulation of acids and water in the oil.

A car driven mostly on the highway at highway speeds , (above 60 MPH,) will burn off all water and acid in about 20 miles of this type of driving , because the engine truly gets up to optimum operating temperature.

In city driving the engine oil and engine seldom if ever reach the same temps as when driven for long periods on the highways.

If you drive mostly in the city it would be adviseable to change the oil& filter every 5000 miles

If your drivng is mostly highway you could probably go at least 7-8000 miles without a problem with full synthetic.

I change my oil every 5000 miles and I drive a 50-50 combo . of city highway driving.(spring and fall)

After all, oil changes are cheap maintenence,and I use Mobil 1 synthetic 5w30 in the summer gray cap and yellow cap in the winter (extended service)

Hope this helps? Ed

I drive my cars untill they are 18 years old, and then sell them. Won't happen with 10,000 mile oil changes, particularly running standard 5W20 or 5W30 oil. I generally pull plugs every 50-60000km. This assures they WILL come out. If they are still good, they may go back in. Seen too many that may as well have been welded in at 110,000km.

ANd not only that, you can bitch and complain all you like after the engine has "coked up" - if you have "neglected" your oil changes it's YOUR pocket that hurts.

I have to admit, that I use fully synthetic Mobil1 on my Audi A4, and change the oil and filter (using an OEM filter) every 5,000 miles. Probably overkill but that's just how I roll..... ;-)

Dan D '99 Impreza 2.5 RS (son's) Central NJ USA