HDEO vs. PCMO... I know, I know...
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Just more robust..
Better fuel economy, longer lifespan of cats and O2's due to less ZDDP.
Better start up viscosity with pcmo, maybe better fuel mileage depending on engine size. On long trip driving hdeos will probably have less wear due to higher hths. Really depends on what you drive and how you drive it. I run an hdeo in my Avalanche in the summer when towing Rotella syn t-6 5w 40, in the winter when i'm not towing i run pcmo mobil 1 0w 30. I'll take shot cats over shot bearings when i'm towing in the summer.
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Is the worry about HDEO and cats even really an issue if your engine doesn't consume oil?
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dnewton3
Staff member
I would tend to agree that HDEOs do have some attributes that could be interpreted to be "better" when looking at a PDS or VOA. However, I have yet to see any evidence that it actually manifests itself in real world UOAs or other concerns such as cats.
Yes, HDEOs are very well constructed, but the same can be said of PCMOs. Let's face it; the same companies that make Delo, Delvac, Rotella, Premium Blue, etc are the same companies that make excellent PCMOs.
Why is there not just one oil from each company? Because market demands and strategies develop into different needs.
I challenge anyone to show me a decent gasser engine (in good mechanical shape) that is somehow miraculously "better" by using HDEO rather than PCMO. Or, better yet, show me a gasser engine that would have been "saved" from peril by using HDEO over PCMO.
The real advantage I see by using a HDEO in place of PCMO is the consolidation of inventory. I'd never use a PCMO in diesel application, but it's generally OK to use an HDEO in a gasser application. If you have a gasser that can tolerate a slightly thicker oil (over 5w-20) and a diesel that can live with a bit thinner oil (less than 15w-40), perhaps a 10w-30 HDEO could serve all. And in reality, most engines can find that compromise close enough to work well in most all conditions.
Overall, I'm a fan of using one decent PCMO for gasser app's and one decent HDEO for diesel app's. It's not like I can't find space in the garage for both.
Yes, HDEOs are very well constructed, but the same can be said of PCMOs. Let's face it; the same companies that make Delo, Delvac, Rotella, Premium Blue, etc are the same companies that make excellent PCMOs.
Why is there not just one oil from each company? Because market demands and strategies develop into different needs.
I challenge anyone to show me a decent gasser engine (in good mechanical shape) that is somehow miraculously "better" by using HDEO rather than PCMO. Or, better yet, show me a gasser engine that would have been "saved" from peril by using HDEO over PCMO.
The real advantage I see by using a HDEO in place of PCMO is the consolidation of inventory. I'd never use a PCMO in diesel application, but it's generally OK to use an HDEO in a gasser application. If you have a gasser that can tolerate a slightly thicker oil (over 5w-20) and a diesel that can live with a bit thinner oil (less than 15w-40), perhaps a 10w-30 HDEO could serve all. And in reality, most engines can find that compromise close enough to work well in most all conditions.
Overall, I'm a fan of using one decent PCMO for gasser app's and one decent HDEO for diesel app's. It's not like I can't find space in the garage for both.
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IMHO it would be very hard to beat M1 0W40 in a passenger car application. It has very good mfg approvals and I'd definitely use it over a mineral 15W40 in a passenger car.
Charlie
Charlie
Startup wear would be MUCH higher with a 15W40 HDEO over a thinner PCMO-it's usually overkill in my opinion, normally a gasser motor doesn't need it.
The most frequent reason for people to run HDEO in a gasoline engine is to get wear protection for slider-follower cams in older cars. In my opinion, there is no reason to run HDEO in a gasoline engine that has a roller cam, as there is no need for 1200-1500ppm of zddp in this type of engine.
And since the advent of ULSD, TBN levels of HDEO's has been dropping to the point where there are many PCMO's that actually have higher TBN. Case in point: M1 0w40 has 11.8 TBN, and M1 TDT has 10.6. So now I'm beginning to wonder: why not run M1 0w40 in my Cummins Dodge?
And since the advent of ULSD, TBN levels of HDEO's has been dropping to the point where there are many PCMO's that actually have higher TBN. Case in point: M1 0w40 has 11.8 TBN, and M1 TDT has 10.6. So now I'm beginning to wonder: why not run M1 0w40 in my Cummins Dodge?
The reason I may use an HDEO; for a period of time anyway, in a PCMO app is as an aid in cleaning up the engine slowly over time, but not at the sacrifice of extreme jumps in viscosity. Say, 0w-20 regularly used and running a full fill of 15w-40. Just my personal preference.
Typically HDEO has a higher TBN, Zinc and dispersant level than a PCMO and higher ash.
But with newer CJ Low SAPS oils that Gap maybe srinking a little. Thought the HDEO is still more robust a will give a longer drian interval than a PCMO.
But with newer CJ Low SAPS oils that Gap maybe srinking a little. Thought the HDEO is still more robust a will give a longer drian interval than a PCMO.
Originally Posted By: A_Harman
And since the advent of ULSD, TBN levels of HDEO's has been dropping to the point where there are many PCMO's that actually have higher TBN. Case in point: M1 0w40 has 11.8 TBN, and M1 TDT has 10.6. So now I'm beginning to wonder: why not run M1 0w40 in my Cummins Dodge?
What you are seeing is the effect of CJ4 (1.0% ash) on truck oils.
If you have a need for a high TBN there are many 15W40s still rated for CI4+ with TBNs up to 15 (Texas Refinery Corp ProSpec III), 40 wts with TBNs up to 17.4 with MB 228.2 rating (Delvac 1440), and a few 5W40s with TBN up to 16 (see my sig.). But you probably don't need it.
Charlie
And since the advent of ULSD, TBN levels of HDEO's has been dropping to the point where there are many PCMO's that actually have higher TBN. Case in point: M1 0w40 has 11.8 TBN, and M1 TDT has 10.6. So now I'm beginning to wonder: why not run M1 0w40 in my Cummins Dodge?
What you are seeing is the effect of CJ4 (1.0% ash) on truck oils.
If you have a need for a high TBN there are many 15W40s still rated for CI4+ with TBNs up to 15 (Texas Refinery Corp ProSpec III), 40 wts with TBNs up to 17.4 with MB 228.2 rating (Delvac 1440), and a few 5W40s with TBN up to 16 (see my sig.). But you probably don't need it.
Charlie
dnewton3
Staff member
TBN is a moot point in most cases. People change the oil way before it's end of lifecycle.
^ Not necessarily when running HDEO in a gasser. In 6k miles, my Jeep had chewed T6 down to 2.4 TBN. Mind you, that did have some shorter than ideal trips in a Rochester winter, but regardless, it wouldn't last 10k in this thing (5 quart sump) unless it was pretty much all highway.
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dnewton3
Staff member
Originally Posted By: rslifkin
^ Not necessarily when running HDEO in a gasser. In 6k miles, my Jeep had chewed T6 down to 2.4 TBN. Mind you, that did have some shorter than ideal trips in a Rochester winter, but regardless, it wouldn't last 10k in this thing (5 quart sump) unless it was pretty much all highway.
Interesting. Is that a single observation or multiple consistent UOAs?
Still - MOST times TBN is moot, even if you are the exception to the rule.
^ Not necessarily when running HDEO in a gasser. In 6k miles, my Jeep had chewed T6 down to 2.4 TBN. Mind you, that did have some shorter than ideal trips in a Rochester winter, but regardless, it wouldn't last 10k in this thing (5 quart sump) unless it was pretty much all highway.
Interesting. Is that a single observation or multiple consistent UOAs?
Still - MOST times TBN is moot, even if you are the exception to the rule.
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Hi,
I started using HD lubricants in petol engines during the late 1950s. This was simply because of the poor quality (relatively) of PCMOs of that era. Engine designs dictated the need
Some engines were transformed by their use and I settled on the CAT (Supplement 3) and MIL specs as the base lines for me. It is interesting to note that both MB and especially Porsche recommended their use too - and Porsche's FF of the time was Shell's Rotella/Rimula products. All were mono-grade
By the end of the 1970s real changes had commenced and over the years the Quality worries were dissipated long ago
This has much to do with OEM specifications and the formation of ACEA. I believe the formation of ACEA woke up API but this had already commenced in the 1980s with moves from the NA diesel engine maufacturers lowering the boom on the API over quality
The need for HDEOs in petrol engines does not really exist today IMO amd IME if correctly specified and OEM Approved lubricants are used
I started using HD lubricants in petol engines during the late 1950s. This was simply because of the poor quality (relatively) of PCMOs of that era. Engine designs dictated the need
Some engines were transformed by their use and I settled on the CAT (Supplement 3) and MIL specs as the base lines for me. It is interesting to note that both MB and especially Porsche recommended their use too - and Porsche's FF of the time was Shell's Rotella/Rimula products. All were mono-grade
By the end of the 1970s real changes had commenced and over the years the Quality worries were dissipated long ago
This has much to do with OEM specifications and the formation of ACEA. I believe the formation of ACEA woke up API but this had already commenced in the 1980s with moves from the NA diesel engine maufacturers lowering the boom on the API over quality
The need for HDEOs in petrol engines does not really exist today IMO amd IME if correctly specified and OEM Approved lubricants are used
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I`ve read HDEO`s *can* be more abrasive than a PCMO in a gasoline engine. I`ve read it here,and on other forums. Is this myth or fact?
Hi,
aquariuscsm - High SA levels can lead to increased wear in some engine families. In the past a high TBN was a precurser in this regard
In general terms a lubricant with a TBN of say 12 and a SA level of 1.3% mass is less desirable than one with a similar TBN and a SA level of 1.0% mass. Newer Add packages have changed this a little
In is unwise to use a HDEO in a petrol engine if it is only API "C?" rated - is should be dual rated (eg C?/S?)
aquariuscsm - High SA levels can lead to increased wear in some engine families. In the past a high TBN was a precurser in this regard
In general terms a lubricant with a TBN of say 12 and a SA level of 1.3% mass is less desirable than one with a similar TBN and a SA level of 1.0% mass. Newer Add packages have changed this a little
In is unwise to use a HDEO in a petrol engine if it is only API "C?" rated - is should be dual rated (eg C?/S?)
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