Is synthetic motor oil better than regular oil?

I’ve been getting a lot of recommendations from my friends to start using a synthetic oil like Mobile1 in my car. I’ve heard a lot of good things about it, but I’m still a bit leery. Can anyone point to any conclusive evidence that it guards against engine wear better than regular oil?

Thank you.

what the people that market synthetic oils forget to mention in all of their adds is that it is not metals wearing off from the motor that the oil filter filters out, it is dirt and grit from the outside world that is getting into your oil. Yes, dirt from the road you drive on finds its way into your engine. It is the job of the oil filter to remove this dirt before it gets circulated around the engine. Another thing they neglect to tell you about are the combustion byproducts. Some of that soot also finds its way into your oil. Granted, at 3000 miles the oil integrity may still be there, but it may also be dirty.

So, to all the people that I talk to that cant seem to understand my point of view, I ask them to at least change the oil filter at the regular interval and just top off the oil to the appropriate level when doing so. Also, use a quality filter. Some do not filter out the finer particles as well as others.

Good Luck!
Drive Safely!

The Auto Answer Man

Oh, sorry. Bob also mentions that synthetics hold up better, and that it’s been proven time and time again…but that isn’t the real issue.

Sorry I do not have a cite at the moment, I’ll post one later if I find it. But I do remember reading some good test data about synthetics. What really stuck out was the burning temperature of synthetic compared to petroleum. The burning temp for synthetic was like three or four times higher than petroleum. That right there is enough reason for anyone who drives a car with a turbo-charger to use synthetic. I have a '96 300ZX with TWO turbos, and to replace them because of coked-up (burned oil) turbo bearings would be insanely expensive. Granted, one should never use a lot of turbo boost then drive the car into the garage and shut off the engine, that’s just asking for trouble. You should always allow the turbos to cool a little before shutting down. But I beleive using synthetic oil gives me that extra-added protection.

Additionally, I have also read that synthetic oil tends not to drain completely off of cylinder walls and bearing surfaces as much, leaving a protective coating for cold starts. But again, I have no cite at this time. This is just from memory from when I was researching this question myself some time ago.

Synthetics have two major advantages over ‘regular’ oil.

  1. Less viscosity at lower temperatures (it doesn’t thicken up as much when cold).

  2. Higher tolerance to thermal breakdown when hot (this minimizes the formation of sludge).

All you want to know seems to be answered in the link below:

Before someone busts my chops on this after reading further through my link I may have incorrectly used the term ‘viscosity’ in my previous post. At the very least it may be misleading. 5W-30 (for instance) oil has precisely the same viscosity in both synthetic and non-synthetic versions (I’m pretty sure that is what the ‘5’ refers to). The synthetic oil is merely more pure than conventional oil so it has less wax (according to my link) that would cause the oil to flow less well at lower temperatures.

Bob the Auto Answer Man is telling people to change their oil filters without changing the oil? Wouldn’t that be a little messy? I guess you could flip the car upside-down, but otherwise you are going to end up with a facefull of oil.

One more cautionary fact: once you switch to synthetic, don’t go back. Switching from synthetic to conventional causes oil leaks. (or was it the other way around? hmmm…)

Maybe it was switching from conventional to synthetic on an older engine is a bad idea… I think that is true too. Hmmm, hopefully someone else can clear this up, but I know switching can cause harm.

Well, I do have one bud who started using Amsoil in a very high mileage car. He said the car all of sudden started using oil like it was nobodies business, when previous to the switch it didn’t lose oil at all.

All cars I’ve changed the oil/filter on had the filter mounted high enough on the block that the filter could be removed without draining the oil. Not to say that’s universal, but in my experience it’s pretty common.

The impression I’ve gained through a fair bit of reading is that:[ul][]synthetic oil is clearly better than conventional oil by most measures of performance, but;[]for street use in most vehicles it’s not “better enough” to justify its considerably higher price.[/ul]You’ll surely find many who don’t agree with this. I use conventional oil in my vehicles and change it at the recommended intervals. I think I have a reasonable expectation of getting very long life out of them.

When you buy a brand new bike you might well be advised to use semi-synthetic oil rather than the fully synthetic high grade stuff for the first 1500 miles at least.

On BMW bikes you may need to use the lower grade of oil for sometime longer.

In fact it actually stated this in the owners manual of my former new Honda CB750(very similar to a Nighthawk)

The reason is that the engine has to be run in first, and using some of the very high quality synthetic oils not only slows this proces down, it can lead to burnishing of the cylinder bores, also known as glazing.
Cylinder bores are not polished mirror smooth, they need a certain amount of minute scoring in order to hold oil on the surface.Glazed bores will mean that an engine will use a lot more oil, very much like Hermann Cheruscan’s case he describes.

Taking the glaze off(glazebusting) is very expensive since the cylinder block has to be removed so that it can be fine sand or bead blasted.

Old engines have much greater(in relative terms) clearances internally either becasue of wear, or because manufacturing tolerances in older engines are greater, in an older design of engine it is inadvisable to use fully synthetic oils, which work extremely well on high revving, high compression, and close tolerance engines.

All that said, Ford makes and sells a small car here called the Fiesta, which is fitted with the Zetec engine.
They specified around 10k miles between oil changes, then suddenly changed that the following year to 20k miles.
The onnly differance was that the oil specified had been changed to fully synthetic type.
This does not change the fact that other parts still need servicing at 10k miles, just that the service intervals were extended.
One example of how disastrous this can be, the toothed belt driving the cams, and water pump etc was inspected every 10k for signs of damage.
When the service interval was changed to 20k to suit the oil regime, it meant that cam belt was inspected half as often too, and this leads to more risk of it snapping, and when it does it is disastrous.

In the UK a 20k service interval on a small car can mean that belt does not get inspected for maybe two years, the belt ages and the risk of failure is much greater, and there is a liklehood the vehicle is out of warranty too.
Often such cars are sold on well before that 20k service, so the potential used car buyer has lots to worry about.

Given the cost of a service is around £120, it seems silly to me to risk a total engine write off costing up to £1500 or more just for the sake of a few litres of oil and a cam belt.

I read an ebook on the subject, and it appears that BOTH can potentially cause your engine to begin using more oil than it did before.
To wit:
A) Going from conventional to synthetic can cause you to start using more oil (the synthetic can clean out the gunk in the engine, causing it to begin leaking)
The author said this would happen in 5-10% of high-mileage cars. I was considering switching from conventional to synthetic around this time, and the 5-10% chance was enough to dissuade me.
Of course, if your had low miles, anywhere under 50K, it wouldn’t seem like there would be too much gunk built up.
B) Going from synthetic to conventional can cause you to start using more oil. This was allegedly because there are additives in synthetics intended to “swell your seals” in an effort to prevent the kind of leaking that was mentioned in point A.
Of course, your conventional oil won’t have the same properties as the synthetic, and when you switch back, you’ll have leaks because your seals have been altered.

I really wish I could have moved to synthetic, because I know my conventional is getting beaten to hell with all of my very short drives to work. (I live under 4 miles from work. If this city was more bike-friendly, I wouldn’t even drive.)