My 04 Celica has appx 50k miles. I keep reading about advantages/disadvantages of using synthetic oil. I live in KY.... gets very hot in summer and very cold in winter. With this mileage and considering the climate in my area.... should my next oil change be synthetic oil? Or is it still to early for this change?

And does anyone know Toyota recommendations on this?

As far as I know there is no recommendation by Toyota on this. Using synth with that mileage should be fine.

I recommend using synthetic now. It will help the engine last longer.

Here's a snippet from http://www.carcraft.com/techarticles/synth...nventional_oil/ that I found to be quite helpful...


Synthetic oils, pioneered in the '70s by Mobil and now available from most major oil companies, take the all-season, multiviscosity approach to the outer limits. Unlike traditional mineral oils that are produced by distillation and further refining of existing crude oil stock, synthetic lubricants are made through chemical reactions. These new oils aren't synthetic or artificial in the sense that they're manufactured out of whole cloth--they still have the same natural ingredients found in "real" oil. But in a synthetic lubricant, these ingredients are recombined like a Lego set to yield synthesized-hydrocarbon molecular chains with desirable characteristics and uniformity not found in even the highest-quality traditional motor oils. Typically, the best synthetic oils use a combination of up to three different synthetic base fluids--polyalphaolefin (PAO), synthetic esters, and alkylated aromatics.

Because a synthetic oil's molecules are much more consistent in size and shape, they are better able to withstand extreme engine temperatures. By contrast, the unstable molecules in conventional oil can easily vaporize or oxidize in extreme heat. Mobil 1 synthetic is said to be capable of protecting engines "at well over 400 degrees F"; in the real world, most racers have no problem running synthetics up to 290 degrees F under prolonged use, but they get really jumpy when a conventional exceeds 270 degrees F.

Because a synthetic oil is chemically produced, there are no contaminants in the oil. By contrast, conventional oils contain small amounts of sulfur, wax, and asphaltic material that can promote detonation as well as varnish and sludge buildup. With no wax, synthetics will flow at much lower temperatures than conventional oils. In fact, synthetic oils are now available with viscosity ratings as low as 0W-30, as in Mobil 1's new Tri-Synthetic blend or Castrol Formula SLX. These oils flow more than seven times faster than a conventional 5W-30 motor oil during initial start-up, yet at normal operating temperatures act like a regular Grade 30 oil.

Wow! Thanks!