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How many miles on synthetic motor oil?

How many miles on synthetic motor oil?

How many miles on synthetic motor oil?

(OP)
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?

RE: How many miles on synthetic motor oil?

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

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!

RE: How many miles on synthetic motor oil?

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.

RE: How many miles on synthetic motor oil?

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.

RE: How many miles on synthetic motor oil?

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.


RE: How many miles on synthetic motor oil?

I second ivymike.

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

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.

RE: How many miles on synthetic motor oil?

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.

RE: How many miles on synthetic motor oil?

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

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.

RE: How many miles on synthetic motor oil?

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!!!

RE: How many miles on synthetic motor oil?

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.

RE: How many miles on synthetic motor oil?

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

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.

RE: How many miles on synthetic motor oil?

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.

RE: How many miles on synthetic motor oil?

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

RE: How many miles on synthetic motor oil?

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.

RE: How many miles on synthetic motor oil?

Quote:

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

RE: How many miles on synthetic motor oil?

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).

RE: How many miles on synthetic motor oil?

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

RE: How many miles on synthetic motor oil?

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.

RE: How many miles on synthetic motor oil?

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.

RE: How many miles on synthetic motor oil?

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?

RE: How many miles on synthetic motor oil?

As many of the members here know, after I retired I worked part time for my ex crew chiefs industrial air compressor company.  Part of my duties was to determine why many of the customers were having lubrication problems with some very large rotary and screw compressors.  What I found was the service intervals for lubrication changes (synthetic oil) exceeded the oil filters ability to adaquately flow oil at the proper flow rate (no bypass on most)...cure, change the filter at mid point of the oil change interval...problem solved.  Based on my admitedly limited experience in the field, I am not at all convinced the "engineers" that concocted the service intervals used much more than a educated guess considering that after many calls, they altered the oil filter change intervals to fit the actual conditions in our area.

Cannot address statements about Toro or the "fact" that oil filters get better with use (??? of course it gets "better" to the point it "filters" 100%!)...I can say that I change filters with oil changes every time and cut my filters open to inspect them, just in case.  Just for drill, cut open a few propriety brands and compare...you will be astounded at what you are relying on to "protect" your investments.

Rod

RE: How many miles on synthetic motor oil?

Agree that a filter gets better with use, but at the expense of reduced flow/increased DP.  Maybe its okay for twice as long, maybe it blocks oil flow or goes into bypass, which negates the purpose of the filter until the next change.  Unlike steam turbines and large diesels, cars, light trucks and lawn mowers geenrally do not have DP gauges.  It just seems light cheap insurance to change the filter with the oil and one less thing to stay awake wondering about.  

RE: How many miles on synthetic motor oil?

drwebb

From my post 31/03/06

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.

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.

RE: How many miles on synthetic motor oil?

Referring to Pat's post---difficulty in determining the point where the differential pressure is high enough to open the bypass---
Not all filters are equal (doh). A high flow racing filter such as a Fram HP-1 has a working DP of around 1 to 2 psi as used on one of my Lotus twincam engines @ ~85psi working pressure in a properly designed race engine oiling system , CLEAN.  Dirty, after several race weekends, ~5psi, the point of change in that cars owners regimen.  We tried a proprietary filter of ~10 micron capability...DP STARTED at 5 psi!  I am not sure of the Fram HP-1, but the equivelent Wix (51515R) that I use is ~40+ micron.

A note, that car was not mine as I still prefer to change oil and filter at no greater than two race weekends, regardless of the DP...(actually I don't even have an extra guage on MY race car).

Rod

RE: How many miles on synthetic motor oil?

I run 10K miles in both my escorts, Mobil 1 and quality filters (Baldwin or Donaldson) Both cars rarely short tripped, so always at temp. I have never done SOS on oil, because frankly I don’t care. If they die, I fix or replace. My rule of thumb is dirty oil is always better than no oil. I figure why create twice as much waste oil if its not needed.
The only bad part from synthetics is they degrade very fast where as conventional petrol oils lose properties gradually and predictably. I have some info on it around here somewhere. Basically syth’s are better until they hit high temperature. Temperature will make the properties drop off the chart. Conventional oils recover much better from this and slowly degrade over time. I have also ‘heard’ companies like CAT, do not push synthetics even though they sell it. Cat seems to know of other issues with synthetics over conventional oils. I am not sure if it has to due with emissions or durability.

RE: How many miles on synthetic motor oil?

optimum.

Your comments re thermal stability of synthetics is exactly opposite all data I have read, and contradicts my first hand experience where synthetic oils have specifically solved problems where overheated mineral oil was causing bearing failures.

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.

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