KenRudd

Just spent a weekend at the track. Eleven sessions over three days burned 6+ qts of oil. Although the engine has always burned some oil during street driving, street consumption never seemed really excessive for a 200K 928, two or three qts. between changes. And records don't show using that much oil at last years DE's ( Although it did increase).

Detailed symptoms:
- 6 qts over 11 sessions ( roughly 5 hours track time)
- Fair amount of smoke from tailpipe on start up after a tracks session, minor or no smoke after normal street running
- No smoke on deceleration that I can see
- Small puff of smoke on track shifting, described as black by driver behind me ( I don't see it obviously)
- No noticeable performance loss
- Always some oil pooled in J in intake and on intake plenum end caps

Car specifics/changes/mods that may be of interest:
- ~211K miles
- 928MS baffle under filler neck
- Just refreshed intake
- Greg Brown Windage and Oil Pan extension
- Filled to top dipstick mark
- No issues seems in recent oil analysis, but that does not include most recent oil obviously

I've been following most of the threads on oil consumption ( Typically GTS centered, but some others as well) and the also researched the piston rings threads.

First, I need a methodology to figure out where the oil is going: Intake? Rings? Other? I already know at least _some_ is going though the intake, based on the pools I see. Once I know where and why, I'll adjust the thread title and work though the fix.

So, should I begin by measuring leakdown and compression? Or review my venting options? Or Other?

toofast928

Ken what type of oil are you using? I have good results with Royal Purple

85euro928

Are you using the pan spacer to add additional oil to the system or to lower the oil level in the pan?

KenRudd

Good question: It was filled with Amsoil 20w-50, but I had to switch to Mobil1 15w-50 as the Amsoil was not available to add at the track

KenRudd

My goal is adding more oil to the system to keep the pickup as submerged as possible to help prevent oil starvation in corners. I understand the possible advantages of reducing windage, etc by lowering oil level, but as I understand it that is primarily to increase power/efficiency, which is not my primary aim.

So, I fill it up to the same upper level.

Alan

Sounds like you start out with more oil and eventually you end up with more clearance for less windage...

Alan

KenRudd

LOL!
Although I like that Win/Win Scenario, I really need to burn less oil.

Should I be focusing first on loss via the rings or loss via the intake? Got a best guess?

hacker-pschorr

Yup

You are adding more oil for the pick-up and your engine is burping it out. That screen over the breather hole is not doing much with the amount of oil being whipped up by the crank, especially with it "topped off" to full.

If you want to keep that oil level in the crank, you need a breather system suited for the track. As every thread on this topic has pointed out, the system on the 928 is street designed, never intended for track use and you are finding out why.

Invest in a good, high flowing air / oil separator that drains to the sump and go from there.

nc_growler

This sounds very similar to my experiences on the track as well Ken.

I use a little on street driving, but I blow out a quart from full after every two sessions or so on the track. I think I notice it even more since I'm driving GR8WHI1TE and it's all over the back of my car when I come in.

I had been worried about this as well. I'm beginning to feel a little better about things after reading Hacker-Pschorr's post.

Not sure adding a track breather to my '91 is in the cards. May have to consider another (928) solution for that...

Stephen

KenRudd

Spoke with a few vendors. There is real concern that this is not just an intake oil ingestion issue, but I'm certain that is at least part of the issue based on my findings, recent modifications and the above comments.
My next step is Compression/Leakdown testing. That should give a better picture of the health of the rest of the system.

hacker-pschorr

I often forget that not everyone does a compression test every spring like I do

KenRudd

The good news is that I get to buy new tools and add another skill to my 928 Resume.

KenRudd

This is the sort of thing that worries me, from GlenL in another thread:

"This is all sounding unfortunately familiar. (Besides un-helpful chattering)

A few years back I was busy trying to control smoke from my engine when driving at the track. Some smoke on the street, too. Turned out to be broken piston rings and piston lands. (The bits on the piston between the rings). The compression numbers weren't bad. Still give that a compression check and look at the spark plugs for un-even color."

Gary Knox

Ken,

My experience with the '89 (130K miles), as well as the '88's I'd run before that was:

VERY little, or no oil burned in highway driving (250 to 6-700 miles to the track). On the track, it depended on what group I was driving in! Green group, almost no oil usage. White group, usually about a quart a day (120 miles or so), black group about a qt every 95 miles or so. At typical DE's, those figures meant essentially one to 1.5 qts per day. I made it a habit of checking oil about 5 minutes before returning to the track for each outing, and adding when it was at about 1/2 Qt mark (I was there when Ed Ruiz ruined his GT engine, because he hadn't checked the oil level before going out for the last run of the day - never forgot that!).

With the '89, I attended several 'open track' DE's, where you could run as much as you wanted to between 8:30 and 4 PM (closed 1 hr at lunch). There, 2 - 2.5 qts a day was the usual consumption with about 4 to 5 hours of actual track time.

I did not have an oil recovery system for the breather in place. IF I'd continued to drive in DE's, that was on my agenda for 2014.

Enjoy the ride, buy some oil - ha.

KenRudd

Gary,
Your experience sounds like my previous experience. This DE was different.