Oil Analysis to Optimize Drain Intervals

[TooSlick]

1) Test your oil three times to determine the maximum drain interval for the engine/oil combo you are using. This is when the TBN drops to 2.0 using ASTM D-4739, or the oil thickens by 25% ....For diesel engines, I'd also include a hard limit of 2.0% on the soot concentration. Depending on the engine, any one of these variables may be the limiting factor in the drain interval.

2) For a gas engine, reduce this max. drain interval by 25% and use this as your standard drain. For a diesel engine, reduce this drain interval by 33% and use this as your standard drain interval....Note: Acid and soot buildup in diesel engines can be very damaging, hence you want to use a more conservative drain interval if you aren't doing regular oil analysis ....

3) If your operating conditions change significantly or you do major engine mods, repeat step #1 and step #2 ....

Tooslick
www.lubedealer.com/Dixie_Synthetics

 

[Gary Allan]

Finally ..someone around here who preaches finding the edge of the envelope and then taking a step back.

 

[berge]

if this is the first synthetic fill in the engine, is it ok to do a UOA or should one wait for the second synthetic drain? I'm fairly certain I didn't get all the regular oil out with just a drain, will that affect/contaminate the UOA to any significant level or is it negligible.

 

[Drstressor]

quote:

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Finally ..someone around here who preaches finding the edge of the envelope and then taking a step back.

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That's because he is a trained engineer.

 

[RF Overlord]

quote:

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Originally posted by berge:
if this is the first synthetic fill in the engine, is it ok to do a UOA or should one wait for the second synthetic drain? I'm fairly certain I didn't get all the regular oil out with just a drain, will that affect/contaminate the UOA to any significant level or is it negligible.

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I asked the same question of one of the technicians at Blackstone Labs, as I had just switched my car from Pennzoil full synth to M1, and I wondered about the same thing...he told me that as long as I gave it time to drain as much of the previous oil as practical (like until it was just coming out in drips), and installed a new filter, the effect should be negligible.

 

[TooSlick]

For a well characterized material, a safety factor of 1.25 is often used. For a less well characterized material, that factor may be 1.5, or even 2.0 - in the case of a graphite epoxy composite, for example.

There is a fair amount of variability in oil analysis results, so you don't want to work too close to the edge....

Berge,

I'd drain the first batch of Mobil 1 after 5000 miles and test the second batch after 6000-8000 miles. For Amsoil, I'd increase these numbers by 50% and do the same process ...

TS

[ February 02, 2004, 10:35 AM: Message edited by: TooSlick ]

 

[TooSlick]

Mike,

Go back and look at all the VW TDI analyses ....

The ones that have < 2.0% soot also have very low iron and chrome wear. When you have high pressures between parts in the valvetrain, you want to keep the soot level as low as possible. The highly abrasive soot particles destroy the integrity of the AW films under these conditions and lead to polishing type wear.

I do think you can probably go up to 3%-4% with a bypass filter, since it removes any agglomerated soot particles ....

Ted

 

[Doug Hillary]

Hi,
TooSlick - regarding diesel engines;
I and (probably Jerry - heyjay) with extensive experience with UOAs in high output diesel engines MUST challenge your comments

1 - The ENGINE and OIL makers soot and TAN ( TBN )and wear metal limits should be determined first. These vary substantially and soot will vary from about 3% to about 7%. A TBN can be allowed as low as 1 under WARRANTY with some engine types.
Especially when using CI-4 lubricants - and more so with synthetics! The synthetic lubricant's chemistry determines the allowed SAFE soot level which may be a long way above a similar API rated mineral oil
Frankly the soot percentage is a percentage - whether you have a by-pass filter or no filter at all. The filters only determine how quickly you reach that figure!
Note: for many years Detroit Diesel had a dual FF & single bypass filter ( three pack ) installed on their Series 60 engines. The bypass filter was deleted about 10 years ago and the allowed soot limit actually was increased with the first CH rated oil

2 - As for 1) above, the OCI will also depend heavily on the factors listed there and the oil and filtration system used

3 - For viscosity read 1) above again and also note and analyse the ACEA "E" ratings concerning viscosity increase and decrease percentages. Some engine makers allow beyond a 40% increase

Remember that Euro makers are producing engines designed around energy conservation. Even with small sump sizes some makers are recmmending 160kkms ( 100k miles ) OCIs and have been doing this for some years. Some with and some without by pass filters of either cartridge or centrifuge types. The USA is really playing catchup here and energy prices will accelerate this process. Iraq is but one step in the learning curve!

As to OCI's I operate many of my vehicles at a multiple of seven (7) times the engine maker's normal OCI! You don't do this lightly with engines costing $A40000+ and in heavily utilised equipment

At this stage I have never experienced engines having soot and TAN reaching beyond the limits noted in 1) above. Nor have I experienced a viscosity increase/decrease beyond about 3 or 4 percent. In millions of kilometers of use and in engines purchased from 1986 to 2003

Many of the UOA's results are of course interlinked - especially when dealing with diesels. Experience in interpretation plays a huge roll as does knowledge of the hardware

But, we have covered this before on here - probably under the TAN v TBN discussion

Guidelines are one thing - we are all learning

Regards

 

[msparks]

Why only a 2% max on the soot?

Seems like the industy caps at 3-4%. I've also heard some folks go over that with Amsoil since it does such a good job at keeping soot suspended.

Also a higher soot allowance would be okay with a by-pass filter. I'd say 6% or so would not cause any long term problems. A by-pass filter will remove any soot that has agglomerated larger than 3 microns, and probably most soot less than 1 micron.

 

[Santo Fontana]

Doug Hillary and TooSlick I appreciate your posts.

Doug, is there a specific name for the spec sheets the manufacturers provide regarding what is allowed in UOAs?

thanks

 

[Doug Hillary]

Hi,
Santo - The Spec. sheets/booklets for heavy diesels consumables are available from the Manufacturer. These cover fuel specs, oil specs., coolant types and etc. They give the specifications required to conform with warranty needs and on going requirements etc.
All have them available but some are reluctant to provide them to end users

The National Service Dept for most vehicle Manufacturers would surely have them - obtaining them is another issue

The previous comments here about adding 50% to the initial Mobil 1 limits when using Amsoil and the performance of non centrifugal by-pass filters concerning soot in various micron sizes need very careful consideration and may indeed be contentious

It is important not to confuse marketing talk with reality. And costs/benefits must be part of the reality trip

Regards

 

[Doug Hillary]

Hi,
TooSlick = the "few litres of Fosters" deal sounds great

Yes the soot's limiting % is one thing that has caused a lot of confusion. When field testing a prototype CF - CH semi synthetic 15w-40 for Castrol over a decade ago we tested to very high soot limits
We were amazed to find:
a) wear metals did not increase proportionally
b) viscosity did not rapidly increase
c) TBN remained well within limits ( min 2 )

At the end we settled on 3% as a realistic limit although we reached 7% in some OC cycles
This engine did not have a by-pass filter

We settled on twice the manufacturers OCI limit at 30kkms and often got to 35kkms within limits of the UOA. We never got near a TBN of 2 but did suffer viscosity increases of about 30%

We noticed the No1 FF filter was about 2/3 full of soft carbon at 35kms but No2 FF filter was virtually empty
We removed the valve cover every 100kkms and no excessive build up was ever evident

Later that engine was sold off with nearly 1m kms up. It had been trouble free and the oil consumption was about 1ltr/5000kms when sold

I have also seen similar engines on mineral CF oils at the time that had excessive soft deposits even at the oil/engine Manufacturer's conservative limits

I have since realised that in the end it is the oil's ability to deal with the soot that is most critical - less so the filters. And the soot % limiting factor depends on the oils' chemistry. Mobil's Del 1 base pack additive suppliers have tesetd the oil to levels beyond 7% without problems. In the real world this cannot be marketed due to all the tangential issues

As well as Fosters we have many boutique beers too. I love your American beers as well which are readily available here

Regards

 

[Drstressor]

TooSlick is basing his recommendation on UOAs from the VW TDI engine. This is an EGR equipped engine with a sliding camshaft follower rather than the rollers used in heavy duty diesel engines. The engine is designed to run on European spec diesel fuel. TDIs operated on North American diesel accumulate soot at a much higher rate than other engines. I have seen the same TDI UOAs as TooSlick and must agree that for this particular engine, wear metal accumulation goes up with soot levels much >2%.

 

[Roger]

quote:

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You will almost never reach the condemnation limits for wear metal concentrations in these types of applications

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What do you consider those limits to be?

 

[satterfi]

quote:

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Originally posted by TooSlick:
1) Test your oil three times to determine the maximum drain interval for the engine/oil combo you are using. This is when the TBN drops to 2.0 using ASTM D-4739, or the oil thickens by 25% ....For diesel engines,....

....SNIP....

Tooslick
www.lubedealer.com/Dixie_Synthetics

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That sounds easy enough. In practice, it will take a lot more discipline than most people here have. Patience and a methodical procedure to determine facts is lacking here.

I don't mean to slam your average poster here, but as one famous .44mag user once said;

"A man's got to know his limitations"

 

[TooSlick]

Doug,

My comments were intended for owners of gas and diesel engine passenger cars and light duty trucks. You will almost never reach the condemnation limits for wear metal concentrations in these types of applications, before the TBN bottoms out or the oil thickens out of grade.

I would certainly defer to you on the topic of commercial engine analysis. However, I would also contend that keeping the soot concentration < 2.0% is a good practice in any case, and will significantly reduced soot related polishing wear.

When and if I get to Aust, we can discuss this further over a few Liters of Fosters ...

regards,

TS

 

[TooSlick]

Satterfi,

You can also test the oil from three different batches and take the worse case result as your maximum drain interval, if you think that's simplier ...

My main point is that you don't have to test every batch of oil, once you determine a conservative drain interval.
I test my three engines once a year, but I'm primarily using the results as a sales tool at this point ....For the first sixteen years I ran Amsoil, I simply changed it once a years and never tested it....

TS
Dixie Synthetics

 

[uw89]

Any difference in the recommendation if the gas engine is a turbo?

Thanks.