Explain this - turbo "issues"...

[steved]

Alright... found this interesting to say the least...

I have been running Schaeffer's Series 9000 5w40 (a PAO oil) for the past few miles (around 30k). Ever since I put it in, the turbo has wavered (slow pulsing) at light throttle... almost like the waste gate control wasn't working properly, and was "hunting" for the right position. You couldn't feel it, may have been able to see it in boost pressures, but you could definitely hear it. The wavering has been with me for the past 30,000 miles... not something that changed after a while, it started with the oil change (at that point I assumed it was coincidence).

Fast forward to Monday, and I decided to change back to conventional Rotella 15w40 since I was seeing no real benefit from running Schaeffer's. Turbo immediately quit wavering. I have driven it 300 miles since putting Rotella back in... not a hint of wavering. I could make it waver on command prior to this.

The viscosity of the Schaeffers is quite a bit higher than Rotella, as reported on my UOAs. Both oils tended to show similar characteristics (wear metals, etc. ). The only outlier was an slight increase in lead running Schaeffers.

Why would simply changing oil (nothing else was touched) cause a change in turbo operation?

 

[JVolpe]

Well if the turbo bearings use oil for suspension/lubrication I can see where a difference in oil viscosity could have an effect. I have not seen any posts or heard anything like you experienced though.

 

[TimothyLong]

I'm with JVolpe on this. Might be that the turbo pulsing was related to the pulsing of the oil pump circulating the high viscosity oil to the turbo bearings. Just a guess.

 

[steved]

The viscosity wasn't that different... we are talking a 5w40 versus 15w40, and still in range.

 

[Wingate]

Its funny that you mention this! I've personally witnessed turbo issues on two different Cat engines from different oils,(both being synthetics) One customer (drilling rig) started using Royal Purple in all his Cat engines, gear boxes, draw works, etc. . Shortly afterward, he started experiencing turbo failures on all three of his 3512B Cats. These were low hour, 1200rpm generator engines. After having new turbos installed, they also failed. Long story short, finally talked to the superintendent and got him to switch to 15w40 Mobil dino oil on one engine, turbo isssues immediately ceased!!. Of course, the salesman that sold them on this also sold them OA's, and said they always came back clean???

The other customer started running schaeffers in a 1200hp 3412E on a chipper, started picking up "compressor surge"... never lost a turbo, but switched back to Rotella and the surge quit...

Maybe one of these oil guru's can give a technical explanation as to whats going on here. it almost seems like some of the synthetic oils "shear" capability gets compromised and due to extremely close tolerances inside turbos (mainly at the shaft thrust) it causes the turbo to drag.

 

[TimothyLong]

Its funny that you mention this! I've personally witnessed turbo issues on two different Cat engines from different oils,(both being synthetics) One customer (drilling rig) started using Royal Purple in all his Cat engines, gear boxes, draw works, etc. . Shortly afterward, he started experiencing turbo failures on all three of his 3512B Cats. These were low hour, 1200rpm generator engines. After having new turbos installed, they also failed. Long story short, finally talked to the superintendent and got him to switch to 15w40 Mobil dino oil on one engine, turbo isssues immediately ceased!!. Of course, the salesman that sold them on this also sold them OA's, and said they always came back clean???

The other customer started running schaeffers in a 1200hp 3412E on a chipper, started picking up "compressor surge"... never lost a turbo, but switched back to Rotella and the surge quit...

Maybe one of these oil guru's can give a technical explanation as to whats going on here. it almost seems like some of the synthetic oils "shear" capability gets compromised and due to extremely close tolerances inside turbos (mainly at the shaft thrust) it causes the turbo to drag.

On this note, I talked with my brother who is a mechanical engineer (he has the brains in the family), and he told me that Cat runs a synthetic in all of their engines now. What he told me was that Cat partnered with Mobil1 to develop a synthetic engine oil specifically for Cat engines and is ONLY available through Cat. This may explain the issue that you stated concerning the customer who switched from Royal Purple to Mobil at the suggestion of a sales rep.



For Steved's problem, this gives me reason to believe that not all synthetic oils (or natural oils) are made the same. On paper they may look equivalent, but the proof is in the engine performance according to what the manufacturer specs are. Still, I would like to hear a more definitive answer from the engine oil gurus myself.

 

[steved]

I guess the above description is what best describes it, surge. It would sit there and woo-woooo-woo-woooo-woo, it also had a very peculiar pitch.



I've been running Rotella and no funny noises, no surging. Just like it never happened... yet it did this for the past 30,000 miles with Schaeffers.

 

[Wingate]

Sorry, wasn't really clear on part of that... . The customer was running Royal Purple due to some slick salesman selling them on this stuff. . After the repaeated failures, I talked to the drilling superintendent and while discussing the failures, I was able to get him to agree to switch one engine on that rig to Mobil 15W40 dino oil. Then the failures stopped.

Yes, all Cat branded oils are actually a joint partnership with Mobil. They have recently been doing some field follow studies with a new Natural Gas oil to replace Peagasus 805 (NGEO SAE 40 wt. ) with Peagasus 1005, but thats still a dino oil... .

I haven't seen any literature as of yet that states the new Cat engines are shipped with synthetic oil. Of course, I work on the industrial and natural gas side (not on-highway or machine) and with Cat, changes start in on-highway, then go EPG and machine at the same time, then industrial and natural gas last. .

I agree, on paper alot of these synthetic oils look the same, but in performance and real-world use, some of them just really don't measure up.

Theres got to be one of those smart oil gurus in here that can enlighten me on exactly whats going on... .