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Increased drain times with synthetic oils

I have been doing a extensive amount of research trying to decide to switch to a “long lasting” synthetic oil. Can anyone give me advice?

Look in your owners manual. Does it say you can extend oil change intervals when using synthetic oil? No! The vehicle manufacterer doesn’t care what type of oil is used because the synthetic oil gets just as contaminated as regular oil.

The benefits of synthetic oil are if you tow with the vehicle, operate the vehicle in extreme heat or cold, if you race the vehicle, or if the engine has a turbo charger. Other than this synthetic oil is a waste of money.


I agree 100% with Tester. It’s false economy to think you can extend the oil change interval past that recommended by the manufacturer simply by switching to synthetic.

Unless the owner’s manual specifies synthetic, or you meet the severe service conditions Tester listed, there is no advantage to synthetic oil, and since it costs more than conventional oil, you’ll spend more money for nothing.

Increased oil life in some synthetics is due to higher additive levels that neutralize acidic contaminants. You may also need to make sure your oil filter can accommodate the increased particle burden if you want to extend oil change intervals substantially. I use regular old mineral oil in all my cars, follow manufacturer’s change recommendations, and have no problems.

Are there any issues regarding changing from synthetic to regular oil at next scheduled change? Seems to me I’ve heard mechanics warn about cross-contamination issues, even w/ residual amounts. Just a bogey-man story?

Tester is correct and changing oil types will not cause any problems.

There are no problems switching from regular to synthetic, or back again. You can even mix them if you choose. In fact, some companies sell a blend of regular and synthetic. Unless the owner’s manual specifies synthetic, the engine doesn’t care which you use, or how often you switch.

You can switch back and forth between synthetic and regular oil all you want with no problem. Afterall, they make semi-synthetic oils. Which is a blend of synthetic oil and regular oil.


I agree with the above, with caveats…if you tow a LOT, or have a turbo, you’ll want to stick with a synthetic.


I also use conventional oil and change it every 3-5K miles. Even with extended change intervals you wouldn’t save much when you consider the extra cost involved with synthetic compared to conventional oil. My daily driver is an '88 Ford Escort and all I’ve ever used is conventional oil, the car is now at 516K miles without any rebuilds and still running great.

Since this thread has drifted to the old synthetic vs conventional oils, I will point out that if your owner’s manual says to use a synthetic oil, you really really want to use a synthetic oil that meets all their specifications.

Synthetic oil (name brand) is better and can last longer because it retains its viscosity under a wider operating temp range. however, the oil filter usually gets gummed up after 8-10 K. cars like Lotus and Porsche allow you to run 10K on synthetics. a bigger deal is getting the oil weight right, check out SAE for climate recommendations, but if you have a new car calling for ZERO weight (like 0W-20) you’ll likely need synthetic.

The benefits of synthetic oil are if you tow with the vehicle, operate the vehicle in extreme heat or cold, if you race the vehicle, or if the engine has a turbo charger. Other than this synthetic oil is a waste of money.

This is the guessing I am talking about.

If engine oil gets to the point that it’s gumming up an oil filter then the filter is not the only thing getting gummed up.

I have no idea on percentages, but I’d bet that a fair number of trashed engines that saw extended oil change intervals were also running synthetic oil the entire time.

Yesterday, I spent several hours on Google, on this topic. Turns out a standard recommendation for preventing sludge is using synthetic oil! That sure sounds to me like a major benefit of using synthetic in ordinary cars!

I also read places which said some cars prone to sludge, the manufacturers have changed to synthetic oil as recommended for that exact reason. I found a place which said one manufacturer even sent out a TSB with that requirement, for synthetic oil, as a fix for a lot of sludged engines. Can’t remember, might have been Audi.

So, I am going to suggest it not only was guessing to say synthetic oil is not needed on most cars, and serves no benefits. I’d say it is actually a wrong guess.

I did find one man who said pretty much the same thing. He also commented Gore won the election, and the “Supremes” stole it. Hohohohahahaheehee.

If you’re going to extend your change intervals more than a couple of thousand miles, you should really get a used oil analysis done. This will tell you the state of the used oil and how much additive package is left. Otherwise you’re just guessing. Google “Blackstone Labs”

If you have any warranty left, I would wait until the warranty expires to do any experimentation, or you will likely not be covered if something happens.