Oil Consumption - update and help diagnose - LONG

[Fuelrod]

When the tired engine was "freshened up" they should have freshened up the parts that needed it the most, the pistons, rings and cylinders.

Rebuilding an engine a little bit at a time is a waste of time and money.

Synthetic oil leaves little smoke when it burns.

Good Luck...

 

[Doug Hillary]

Hi,
Fuelrod - your comments re "freshening up" were covered earlier

Many service Providers do not carry out an accurate diagnosis before commencing work on the obvious

In the case of the Porsche 928-944 engine families - their longevity is legendary. Many 928s for instance have covered near 1m kms without a teardown. However the running in process (and some other design issues) caused some engines from about MY89 onwards to consume oil. Many were fixed under warranty but many - due to low annual use - were never touched
Unless the engine's history was taken into account (oil useage and etc) the reringing and bore finishing would have been considered overkill. The teardown requirement usually relates only to the head and valvegear.

If this was the case in this S2 Porsche engine the rings should have been replaced and the bores should have been finished as per Kolben-Schmidt Porsche's specifications! That is what I would have done considering the distance on this engine and the nature of the work carried out in two stages!

Simply, it wasn't done

I have just completed a teardown inspection at 1m kms on one of my 500hp DD-MTU diesel engines. All parts were suitable for reuse. I reringed it!
It has now done 30k kms on Delvac 1 5w-40 without a trace of oil use. This is after an initial 2000kms of normal fully loaded road use on a mineral oil to detect leaks etc and then a 30 minutes full power dyno bed in!

Regards
Doug
MY02 Subaru Outback 2.5 manual (Delvac 1)
MY98 BMW Z3 2.8 manual (Delvac 1)
MY89 Porsche 928 S4 Auto (Delvac 1)

[ January 23, 2005, 04:39 AM: Message edited by: Doug Hillary ]

 

[Gary Allan]

quote:

---

A new unit was installed.

---

My only thought is that this could explain how oil can indeed leak ..without detection. It would only leak (assuming that the thermostat doesn't circulate a minimum amount of oil while closed) when oil temp exceeded the threshold. You would probably not be at these temps except under high accelleration or at highway speeds. If the leak was located where it would not accumulate on the under carrige or elsewhere ..you would see no drips in your drive way ..either on ingress or egress since the oil would probably be cool enough.

When the likely causes aren't yielding the answers ..you stretch and look toward the unlikely....

 

[peterr]

Hmmmmm. Interesting. I had really only thought about temperature from an environmental or overall engine temp point of view rather than something related to the oil cooler thermostat specifically.

My only recent significant Hwy trip did seem to consume more oil. Was doing between 55 and 85 along a 100 mile trip each way and saw increased loss.

My daily commute tends to involve more gradual warm up through traffic and then a leisurely HWY pace.

quote:

---

Originally posted by Gary Allan:

quote:

---

A new unit was installed.

---

My only thought is that this could explain how oil can indeed leak ..without detection. It would only leak (assuming that the thermostat doesn't circulate a minimum amount of oil while closed) when oil temp exceeded the threshold. You would probably not be at these temps except under high accelleration or at highway speeds. If the leak was located where it would not accumulate on the under carrige or elsewhere ..you would see no drips in your drive way ..either on ingress or egress since the oil would probably be cool enough.

When the likely causes aren't yielding the answers ..you stretch and look toward the unlikely....

---

 

[peterr]

Gary

BTW, i did test the other day coasting down a hill in third gear and then hammering on the throttle. No smoke whatsoever. This was with a warmed up engine after about 20 minutes of driving, which appears to be a major factor for me.

This morning was a little bit warmer, maybe low 20s Farenheit. On my way to work about 1 minute after engine start , as I am pulling away from an intersection, a minivan cuts in front of me. I hit the brakes to avoid rear ending him, slowing my car almost to a stop and then accelerated hard in 2nd gear to avoid being rear ended myself. Not much over 3000 RPM. Big puff of smoke/steam. More carbony gray and water vapory white than oily blue.

This is the only scenario in which I see smoke. Cold engine. Hard acceleration.

quote:

---

Originally posted by Gary Allan:

But a somewhat fail safe test for rings would be to coast down a long grade in a lower gear (high vacuum) and then switch to accelleration ..this should produce a noteworthy cloud of blue smoke. This won't necessarily be conclusive proof of bad rings ...but if you have bad rings ..it should occur (sorta like older DNA testing being better at excluding you .then including you).

Good luck!

---

 

[Dr. T]

Peter, mechanical issues notwithstanding, why would you (or anyone) ever use conventional 5w30 oil in a German machine? Ouch.

Try Syntec 5-50. I'm in Mississauga and use this year round. You will have lower consumption than anything from Mobil 1 or any conventional oil...

 

[peterr]

Dr T

Am running Dino due to current application of AutoRX. Frank indicates a preference for Dino in Clean phase and a requirement for Dino in Rinse phase. Admittedly this is probably a question of degree, and perhaps moot if Syntec is really a Group III.

My preference would be to run Mobil 1 15w50 Summer and 0w40 Winter, which is what I ran on my previous German machine. If after the completion of the AutoRX treatment things have improved I would look at going to something like the M1 or the Syntec which perhaps is a good straddle.

quote:

---

Originally posted by Dr. T:
Peter, mechanical issues notwithstanding, why would you (or anyone) ever use conventional 5w30 oil in a German machine? Ouch.

Try Syntec 5-50. I'm in Mississauga and use this year round. You will have lower consumption than anything from Mobil 1 or any conventional oil...

---