I just bought a car with less than 10,000 miles on it and the previous owner mentioned that his previous oil changes were done with synthetic oil. I’ve read elsewhere that you shouldn’t use regular oil after synthetic oil has been used. Any truth to that? There are mixed messages about this on the web.
Is synthetic oil overall better for a car? Should I just stick with the synthetic oil?
Since the previous owner always used synthetic oil, I would stick with it.
It is a little pricey, but longer times between oil changes negates some of that. (Don’t forget to replace the oil filter regularly, even if you let the oil change go up to 10,000 miles) I have heard of some going up to 15000 miles between oil changes with synthetic. But I wouldn’t go over 10,000. And 7500 would be better.
Supposedly you get better gas mileage with synthetic too.
The “don’t go back” rule originated when synthetics in the mass market were new and virtually the only synthetic you could find in most stores was Mobil1 5W20.
Back then there were seal compatibility issues and incompatibilities between synthetic oils and mineral oils.
Those issues are in the past now.
Go back to mineral oil if you wish.
Some cars must have synthetic oil due to their makers speccing it.
What car is this, if I may ask? Make/model/year/engine?
After much research, I have concluded that the only quantifiable advantage to running synthetics is having to change the oil less often if you use Amsoil or Mobil1 Extended Performance, and then only on CONVENIENCE grounds. You’ll never save enough on the labor from oil changes to make any noteworthy cost savings. Regular oils are $1-2 per quart, good synthetics are $4-7 per quart.
Synthetics DO NOT save gas. Thinner oils save gas. Mobil 1 makes it seem like you save gas by using their 5W30… and you do. But the trick is their 5W30 is one of the thinnest 5W30s out there. Much lower and it’d be a thick 5W20.
Just anecdotal, but I’d stick with whatever the manufacturer recommends. We found this out the hard way when my husband decided to use regular oil instead of the recommended synthetic. It was not fun at all being stuck on Route 22 just outside of Newark. Not fun at all, but when a flashing red message comes up on the dashboard saying STOP ENGINE NOW, well, I do as I’m told.
Another is starting at very low temperatures. The difference in viscosity at -20F is quite significant.
Sorry for missing that. Very good point! A good synthetic 0W30 will flow nicely at -45 F or even lower. Living in Ohio, I never really see temperatures below the -25 F that 5W-something oils are good down to.
The other point about keeping synthetics in cars that reccomend them is well-taken. One hot day’s drive in a Corvette that takes Mobil1 from the factory without synthetic in can cost you more than I make in two months.
your in a catch 22 here …
thinner oils save gas … but there is no way you could get a workable 5W30 or so from mineral oil … al these “extreme viscosity” oils have in common that they can be extreme visc. b/c they are synthetic
so they save gas b/c of their low viscosity - and they have the low viscosity (better said: extreme cold-to-hot viscosity range) due to the fact that they are synth.
cheers
alfred
5W30 motor oil formulations do not require synthetic oils. You can make 5W30 out of refined mineral oils and conventional motor oil additives.
Wal-Mart markets a 5W30 non-synthetic oil that meets the API SM spec. It sells for less than $1.25 and is most definitely NOT a synthetic.
Maybe you’re confusing “additive-free” with mineral oil?
A “synthetic” motor oil is one with base stocks that are non-petroleum or have been removed from their original petroleum state by extensive re-refining. Such an oil will be 85% or more, by volume, made of base stocks consisting of Group III, Group IV or Group V as defined by the API.