Synthetic oil

I was told that after your car has done over 25,000 km, you shouldn’t switch from regular to synthetic oil.

Is this true and why?

Not true, switch back and forth at will, no problem. Make sure you use the correct weight, change at correct miles/kms.

That’s not true. You can switch back and forth between regular and synthetic oil at any time.


I know of no reason and/or rationale for not switching to synthetic based on 25K km. You can switch back and forth if you wish. There are number of “myths” like this one that are not based in fact.

Not true. You can switch back and forth between conventional and synthetic (if you want to) any time. The engine doesn’t care which type of oil you use.

If you want to, you can switch back and forth as often as you want and it shouldn’t cause any problems. In fact, I might wait to make the switch to make sure the vehicle is broken in properly with conventional oil.

Of course this all assumes your car doesn’t require synthetic oil, which means switching at all probably isn’t necessary.

That story came out when synthetic first became available. It was to a minor extent true back then, but not today. Today both the oils and the cars are different. You can always switch to synthetic and you can go the other way as long as the manufacturer does not specify synthetic oil.

Unless you drive in severe conditions, I don’t know why you would want to switch to synthetic oil. Mineral oil is perfectly acceptable. Your car will perform as well with mineral oil as synthetic in most circumstances.

Thanks Gang. The question arose because I know someone moving to a cold winter climate with no easy access to a block heater plug in. Cranking problems in the morning with regular oil.

Where the heck is this person moving to that a block heater is needed??? Alaska???

Mike, it can get pretty cold in Northern Minnesota, if you have to park your car outside. Many have block heaters, but for those that don’t I recommend 0W30 synthetic oil which has a pour point of -50F and a “borderline pumping” point of about -40F.

Once travelling in this area I checked into a motel and plugged my car in, not having light oil in the engine. During the night someone kicked my cord out and the engine was very hard to start the next morning. The temperature was about -38F. A 0W30 synthetic allows easier starts and greatly reduces engine wear.

Docnick, I know it can. But some people think that West Virginia is cold after living all their life in Houston. Just trying to clarify.

Once you are used to operating in a cold climate it sort of becomes second nature. I did a stint on the Beaufort Sea (Arctic Ocean) in the eighties. We had oil pan heaters, block heaters, interior car warmers and the vehicles sprayed with a foam underneath to retain more heat. Starting a car at -67F is an experience. If you started your tape deck before the car warmed up the machine would instant pulverize the tape into flakes.

One of the most interesting experiences was helping set up a course in Cold Weather Engineering with University of Alaska.