Going from Synthetic to Regular Oil

[rivieraranch]

We have a 2000 Buick Century that has 36,000 miles. A couple of years ago we started using synthetic oil in it. The other day we had to have some repairs done and the dealer installed regular oil in the crankcase. We had done a synthetic change 2 months ago. When advised that the wrong oil was placed into the crankcase, the service advisor maintained that it would not do any harm to the engine.

Will it?>>>>>>>>

[Drew Dowdell]

the service advisor is correct.

[Guest MikeBike]

We have a 2000 Buick Century that has 36,000 miles. A couple of years ago we started using synthetic oil in it. The other day we had to have some repairs done and the dealer installed regular oil in the crankcase. We had done a synthetic change 2 months ago. When advised that the wrong oil was placed into the crankcase, the service advisor maintained that it would not do any harm to the engine.

Will it?>>>>>>>>

Almost all synthetic oils specify that they can be mixed with conventional (crude stock-based) oils. That being said, there are many inherent benefits that are derived from using synthetics in the crankcase, in spite of their higher cost (improved fuel economy, better performance, longevity, cold-starting advantage, cooler running in extreme hot conditions, cleaner engine, and so on).

In your case, the dealer did what made good business sense to him; put cheaper (i.e. conventional oil) in your engine. While this will do no harm (assuming the oil viscosity is the recommended one for your engine - 5W/30 vs. 10W/30 and so on) when mixed with the synthetic already in your engine, at your next oil change interval (say every 3,000 miles or 5,000 km) or 4 months, whichever comes first, it would be a good idea to replace with a new oil filter and complete synthetic oil in the crankcase if you wish to retain the benefits that prompted you to use synthetics when you purchase the vehicle.

Synthetics are superior lubricants period. They have been around for 50+ years and are standard fare in aero engines, very cold climate applications, and in racing cars. The main difference in synthetics vs. conventional oils are 1) The base stock in synthetics are esters (compressed natural gas vs. crude oil base in conventionals), and 2) the additive package. The additive package in synthetics is almost 100 per cent effective due to their very pure base stock, and as any petro-chemist will be happy to tell you, the additive package is the real secret behind any good motor oil.

For the record, I have been using Synthetic oil in my Chevies for over 15 years (and live north of the 49th). This is a relatively inexpensive insurance policy for your vehicle's engine and the engine subsystems, if you are planning to keep your car for any number of years.

So, to sum up, your dealer's service advisor was correct; no damage will be done. You might want to hit up the dealer for a "free" oil change and filter during your next visit, as a measure of goodwill. These guys tend to have short memories when it comes to customer loyalty and these days, GM is not in an enviable position with slumping market share and billion dollar bleeding on their financial statements.

[76ChevyTrucker]

Hell, you could go back and forth between synthetic and dino-juice per oil change if you wanted. Its never the TYPE of oil, its always the weight of oil that makes the difference.

[daves87rs]

Hell, you could go back and forth between synthetic and dino-juice per oil change if you wanted. Its never the TYPE of oil, its always the weight of oil that makes the difference.

Agreed. though I might not want to do that in an older engine...

Or one with well over 100,000 miles...

I've left the wagon on it's own dino oil....with so many miles, I do not want leaks everywhere...

Her car has has mobil 1 since it turned 10,000 miles...

My neighbor's cobalt is going to start with a blend-then get Mobil 1 (or Valvoline) after it hits 10k itself..

(he bought it used with 2500 miles on it..)

[76ChevyTrucker]

I would go with Mobil 1 since it is one of the oldest Synthetics out there.

[daves87rs]

I would go with Mobil 1 since it is one of the oldest Synthetics out there.

Agreed.

[chipawah]

from what i heard and understand once you go to synthetic oil it is not good to change back to regular oil because it can burn your valves but i do not know but i asked a mechanic at the local repir shop and that is what they told me

[daves87rs]

from what i heard and understand once you go to synthetic oil it is not good to change back to regular oil because it can burn your valves but i do not know but i asked a mechanic at the local repir shop and that is what they told me

If you're driving a Geo Metro, maybe.

Other than that-it's total B.S.

Years ago that could have been said-but Today's oils are so advanced, even dino oil will protect that engine pretty well....

The only reason I used Mobil 1 is that we do quite a bit of city (stop and go) driving, which can be harder on the oil and engine.

I try to baby my engines.....