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Is high mileage oil really worth it?
- Thread starter Exterous
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JulesMaximus
No Lifer
Sure, if you want oil leaks.
I'd stick with whatever you've been using.
radioouman
Diamond Member
Not worth it. Checking your oil regularly and changing it regularly are the most important things that you need to do.
JeffreyLebowski
Lifer
sure if yuo like watching more expensive oil pool on your drive way.
Some high mileage oil is just a heavier blend than the regular stuff.
Zenmervolt
Elite member
That's a myth. Synthetic will never cause a leak. Never.
It does, very occasionally, make pre-existing leaks appear more serious because it flows a little better, but it will not cause a leak and as long as the engine is in proper shape, there's no reason to worry about it.
I have switched several cars to synthetic at over 100,000 miles with absolutely zero problems.
ZV
I've never understood why people defend Synthetic oil not being the cause of leaks like it is their 1st born. Here's my take on it...it you have a car that has alot of miles on it, and has minor or no oil leaking, and then you install Synthetic oil and it starts leaking like crazy...the synthetic oil is guilty by association. If you had continued using conventional oil, the leak would have continued to be minor for a while, taking much much longer to develop into a major leak.
Is the reason that synthetic oil is associated with the leak noble, well sure. The thing is, a large % of cars with alot of miles on them have some sort of leak that, as ZV said, should have been taken care of with good maintenance. The problem is, if you're driving a $900 93 Honda Accord, do you really want to go spend $100-$300 at a mechanic to get the leak fixed? Hell no. BUT, if you're the type that would screw a plywood spoiler on the back, and beleive claims that Synthetic oil restores power, and you use synthetic oil in your car, then now you're stuck with a $900 Exxon Valdez thanks to synthetic oil.
JulesMaximus
No Lifer
No, it won't cause a leak but an engine that leaks a slight bit or is older might start to seep out a little oil after switching to synthetic. I had an older car that wasn't very well maintained and put a thinner oil in it once and that sucker started leaking like a sieve.
I say why bother? If it's working fine now switching to synthetic isn't going to benefit the motor in any way.
Demon-Xanth
Lifer
If it starts leaking oil, step up a weight. Synthetics don't cause the leaks, just show them. Saying that it causes a leak implies that somehow it eats at the seals and gaskets.
Zenmervolt
Elite member
If you're driving a $900 car and can't afford to fix the oil leak, you can't afford synthetic oil and aren't asking this question in the first place.
The problem is that, as this thread shows quite clearly, any time someone mentions switching to synthetic on an older car, people come out and say that it will leak. They do this without bothering to ask about the condition of the car, what kind of maintenance it's had, or anything else. Nope, they just give a blanket statement saying it will leak. Which, by the way, is exactly what you did.
If you and Jules had said, "If the car has been improperly maintained it's possible for synthetic to exacerbate existing oil leaks, so I don't recommend it.", there would have been no reason for me to post. But you didn't. You gave inaccurate blanket statements.
ZV
JulesMaximus
No Lifer
Well, oil leaks are a distinct possibility with a car with 250k miles on it. I was simply playing the odds.
What is there to gain by switching to synthetic at this point?
High mileage oils generally are higher in the cSt department than the other oils in their @100C viscosity class. What this means is if you take say a regular dino 5W or 10W-30, it'll have a cSt @100C in the high 9.9's or low to mid 10. If you go take a High Mileage 5W or 10W-30, it's cSt is going to be right at the top of the 30 weight range...most likely 12.something cSt @100C. Many/Most/All (it's not 100% known) of the High Mileage oils will probably have some additional seal swell adds in them to swell your seals to help stop leaking/oil consumption. The also will probably have small % of a PAO in them, which is a good thing as that's true synthetic (Group IV).
In general, except for the fuel mileage hit (whatever that is) by running a higher viscosity oil compared to just a regular dino, using High Mileage oils even in newer engines would be fine, and in some cases, maybe even preferable.
As far as synthetics causing leaks: This is generally because the engine has been on a diet of dino oil, and most likely not have had the OCI kept like it should (i.e. too far on the oil). So what happens is that the seals start to get degraded/dry, and sludge builds up. The sludge actually acts as a false seal. Then someone decides to put the synthetic in, which not only flows better than the dino*, and in many cases has more detergency, and Whamo, you get the 'Synthetic causes leaks' thing.
*Flows better is accurate. Commonly you see the 'Synthetic is thinner' comments. This is not the case. If you look at the @100C cSt values for synthetics, they are right in line and sometimes even higher than the dino's they replace. Synthetic flows better, it may or may not be thinner...that's totally dependent on which two oils are being compared.
As far as putting synthetic in your ride:
Even if you did a steady diet of proper OCI's, your engine will have sludge, and the ring packs will be sludged up. If you actually want to clean the engine out (for the oil system out at least), then before going to synthetic, you should do an Auto-RX regime first. Then, once you've completed that, you can go to synthetic and not look back. The bennie there is that the gas mileage bump you'll get will end up saving you some real $$ depending on the miles you drive... You can check Auto-RX out at BobIsTheOilGuy.com Forums, go to the Oil Adds forum.
Hope this helps...
Chuck
P.S. I'm not affiliated with Auto-RX in any way, just another one of the very satisfied users...
No, he's providing the correct information, not just a blanket misinformed opinion. I have also switched several high mileage engines to synthetic. Synthetic does flow marginally better, and may leak easier than conventional oil, but it does not CAUSE leaks like everyone else here is claiming.
I have had mixed results in switching too, the 06 Altima had no noticable improvment going from dino to mobil 1, my 2.0L 95 Avenger went from 35-->40 mpg
Zenmervolt
Elite member
I appreciate the attempt to bait me, I really, really do. But it ain't gonna happen.
ZV
Bignate603
Lifer
I agree, if your car is running fine just keep on doing what you're doing.
nerp
Diamond Member
Myth.
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