How many miles on synthetic motor oil?

[Prototyper]

My research indicates that your common gasoline engine can be driven about 12,000 miles between oil changes before contaminates become a concern for induced wear. Some feel a filter change half way is a good idea. Any experiences with extend synthetic oil change intervals?

 

[NickE]

I have no direct experience with extended drain intervals since I have a turbocharged vehicle. However these people may have some info for you.

http://www.amsoil.com

I always thought that the life of the detergent package was more critical to oil life than amount of contaminates.

Nick
I love materials science!

 

[BobM3]

For the past 10 years I've gone a year (10-12k miles) between oil and filter changes (using synthetic oil). No problems so far.

 

[dgallup]

I've never really understood the filter change more frequent than the oil change concept. If your engine is generating that much tramp metal it is a gonner already. I use Amsoil ASL 5W30 and change every 6 months regardless of milage.

 

[ivymike]

FYI, this has been beaten to death in the automotive lubricants forum of this site. My last car recommended 15000-22000mi between oil changes (synthetic). Oil analysis showed that the TBN was getting pretty low at 21k-mi, but the oil wasn't acidic yet, soot was low, wear metals were low, viscosity had crept up quite a bit. I suspect that changing the oil much sooner to avoid the vicosity increase would have paid off monetarily, if I exclude my inconvenience to do it.

 

[patprimmer]

I second ivymike.

This has already been extensively covered. Try a site search.



Regards

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[drwebb]

A filter will strain out finer and finer debris as it loads until the flow stops completely. On an oil filter this is avoided with a bypass valve- but the moral is still that an oil filter should get better and better right up until it starts to fail.

Lots of oil heads like to change their filters frequently, but usually don't have more than supposition that it's failing- or just a 'good idea'- to justify it.

 

[patprimmer]

The problem is that you can't predict when it will become restrictive enough to cause the bypass valve to open occasionally, allowing some previously filtered larger particles that have settled in the bottom of the filter canister to enter the main gallery.

I change filters every time I change oil.

I try to use filters without a bypass.

I did run good synthetics at double the recommended change interval, however with current change to longer OEM recommended change intervals and OEM specified synthetic oils in some cases, I am now less inclined to extend oil change interval past 10,000 kilometres.

The factor that limits oil life in most cases is Total Base Number (TBN), or the ability to resist exposure to blow by gasses without the oil turning acid.

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[kakarot]

patprimmer, its easier that you think.
in the morning, simply count how long it takes to the light go off for oil.
on my car (audi 90 1995 2.8 V6 189K miles) it takes no more that 1 sec to go off. on fresh oil. but when its is old it takes up to 3 seconds to go off.

and please dont reliai on these numbers, each engine is diferent, as well each woman is diferent. I give no more that 7000 miles. if oil goes black then simply change, what is gona hurt 45 buks, or 30 if you change your self.

I dont care about how long can I go, I care how should I care!!!

 

[rpmag]

I found it interesting that in the service manual for my vehicle, city driving was defined as 'harsh conditions' and more regular oil changes were stipulated. I am assuming that the propensity for short journeys where the engine does not get up to full operating conditions would result in the 'harsh' description.

 

[patprimmer]

The amount of time the car spends in lower gears and at idle is greater in city driving, and therefore the engines does more revolutions per mile travelled

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[patdaly]

rpmaq:

City driving also frequently never lets the engine reach full operating temperature long enough to help rid the oil of condensates. It also tends to see more full rich warm up time that helps dirty the oil.

 

[rpmag]

do the condensates add to the development of 'acidity' as described on this forum?

 

[patprimmer]

The combination of water and acid forming gasses contained in blow by make acid in oil.

You need both, but you don't need much water.

More than enough water is also contained in the blow by along with the acid forming gasses.

Regards

eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[evelrod]

patprimmer, its easier that you think.
in the morning, simply count how long it takes to the light go off for oil.
on my car (audi 90 1995 2.8 V6 189K miles) it takes no more that 1 sec to go off. on fresh oil. but when its is old it takes up to 3 seconds to go off.

All I can do with that is smile...

In addition to increasing acid levels you have a steadily decreasing level of additives...antifoam, dispersants, ZDDP and whatever... lowering the ability of the lubricant to handle high temp and high loading.

Not changing the filter??? Your going to spend ~$30 (in some cases much more) on a quality synthetic oil and cheap out on a $5 oil filter?

Rod

 

[BiPolarMoment]

Cheap 5 dollar filter? For my car, 3 bucks would be cheap and a factory filter is about 6. I've read many filter studies concerning my car (Miata) and just about all of them would recommend Purolator Pure One if you couldn't get an OEM one--and that's only 6 dollars as well. Also some of the advance auto branded ones have nearly identical construction to the better filters. Do you buy K&N Oil Filters or something? I buy OEM and stay away from FRAM (some may be good but it's not worth the risk).

 

[evelrod]

I have used Wix filters for so many years I cannot recall the first. I use Wix Racing filters on the race engines and Wix heavy duty on my diesel trucks. No problems, mate.

Re read the post, I did not say anything about 'cheap filters'...I did refer to the 'cheap' individual that would change the oil without changing the filter, too! I buy my oil and filters wholesale, by the case...don't know exactly how much the are individually...it matters not as I won't use any other brand, anyway.

Rod

 

[BiPolarMoment]

Oops, I interpreted "cheap out on a 5 dollar filter" as meaning spend only that much (instead of a more expensive one)--I didn't see the reference in the previous post to not replacing it at all.

I've heard good things about Wix as well, though don't think I've ever seen one in person. I only worry about my single car so buying by the case is sort of an exercise in predicting how long I will own the car. I bought 6 at once a couple years ago--I think I have one or two left, which is going on my car this weekend more likely than not.

 

[TheBlacksmith]

Amazingly, I still see recommendations to change the filter every other oil change! Am considering a new Toro lawn mower and am looking into one with overhead valves and pressure lube. Downloaded owner's manual lists an oil change every 50 hours, filter every 100 hours. Rest assured if I buy the mower, I will try to find the scratch for a new filter every oil change.

 

[drwebb]

Alright Blacksmith, since you judge the recommendation explain on what basis you ascertain that changing the filter every oil change is superior? As pointed out, a filter should get better with use.

Most lawn mowers are air cooled- making them severe for oil contamination- and run at constant speed, making them mild for wear debris. So it may be the filter can take 100 hrs but the oil can't. What mistake did the Toro engineers make with their recommendation?