Can Long-drain synthetics exceed OLM parameters?

[Tucson Five-O]

Hey Guys,

Subsequent to yesterday's question re: Syntec or PP for my 3.5L Chevy, I started thinking about the GM OLM.

My engine only specs dino to comply with the OLM which can go up to 12.5K under optimum conditions.

Obviously, per previous posts from others including a GM engineer, the ZDDP levels were monitored during the individual engine testings in order to develop the algorithm that works so well today. Presumably TBN of the oil as it was depleted was monitored as well.

My question for today:

Do today's long-drain synthetic oils, such as Mobil 1 EP, Castrol Edge, and Amsoil SSO allow for slower ZDDP depletion, perhaps due to improved base stocks and better chemistry?

I know that Valvoline SynPower, although not advertised as a long-drain oil, does mention using a more slowly depleting ZDDP package.

We know that the TBN deteriorates much slower in these long-drain oils, as well as starting higher in most cases. If I was to do a UOA on a premium conventional SM GF-4 oil such as Pennzoil or Chevron, measure the TBN at 0% on the OLM, will a long-drain synthetic like those above, whether they are API certified or not (this isn't a warranty compliance discussion), ran out to an extended OCI, with the OLM reset as needed, until the TBN is at an identically low reading (~1.0), still have adequate ZDDP for valvetrain protection?

Or does the ZDDP deplete sooner than the TBN does, making it highly questionable, if GM was actually testing these long-drain oils, perhaps to recalibrate the OLM algorithm, that the extended OCI can be achieved with adequate engine protection? Because if ZDDP levels deteriorate as fast for those long-drain oils as with premium Group II+ conventionals, then realistically how can drain intervals be extended?

I know that Mobil1 lists 800/900 ppm as the nominal values for the Phosphorus/Zinc levels on their EP oils, which is the same as their standard Mobil1.

Or what am I missing in this analysis?

Thanks,
Gary

 

[m37charlie]

What about >100,000 km OCIs in Mercedes truck engines using 228.5 oils? Or for that matter using P I don't think the limiting factor is ZDP depletion but rather TBN depletion and soot buildup. All mitigated by addition of make-up oil.

Charlie

 

[Doug Hillary]

Hi,
some Oil Monitoring systems are especially calibrated for Manufacturer Approved lubricants

In my Detroit Diesel Series 60 engines (500hp @ 1800rpm, 1650ftlbs torque @ 1200rpm) I averaged 90kkms OCI over many years. This was at a utilisation of around 240kkms per annum. The condemnation points were always either Iron (150ppm) or Soot (3 to 4%) levels - never TBN or TAN. The longest OCI was 130kkms. I used Delvac 1 5W-40. I used Mann-Hummel centrifuge cleaners too - this was cleaned at every second OC but FF filters were replaced at OC. SS FF inserts were later cleaned at every second OC

 

[Corvette Owner]

Unless your car specifies synthetic oil (and comes with it as a factory fill), your OLM is calibrated for Dino oil. As such, you can go longer with a synthetic. My daughter's 2004 Chevy Malibu's OLM sometimes goes to almost 9,000 miles (she does a lot of highway driving). I use Mobil 1 in it and change at 0% oil life anyway. If she goes past 0%, no big deal.

I think, in most normal cars, synthetic oil can go for 10,000 miles.

 

[tig1]

I used to work with a guy that doubled his OLM with M1 5-30 and he never had any problems.

 

[Tucson Five-O]

Corvette Owner,

You'll agree that ZDDP depletion is one of the main parameters that the testing for the OLM monitored right?

This is independent of TBN depletion, or is it? Maybe JAG or MolaKule or Doug Hillary could shed some light on this. Does slower TBN depletion mean the ZDDP is being depleted slower as well? I mean, is that all you have to look at, the TBN?

I know individual engines, such as diesels with the soot are different, as are new engines with their high break-in metals, where you would want to reduce the OCI to remove this potential abrasive "slurry" early, but how do you monitor ZDDP depletion in an engine that doesn't have an OLM?

After all, I don't see much difference between Phosphorus and Zn levels in most VOA's and UOA's.

I'm just trying to get my head around, using a great Group II+ (Pennzoil/Chevron) oil and analyzing it when the OLM says it's shot and calling that my baseline depleted oil, what factors other than TBN (if any other than high wear metals exist) you use to say the extended-drain oil is shot.

Sorry about rambling on.

Take care,
Gary