BruceWard

So its been about 2500 miles and four months since I changed the oil with Mobile One 15W50. Mostt of those miles have been hard street or autocross miles. I parked the car on the sloped driveway to wash it Sunday and then noticed the "Engine Oil" light on when I moved into the garage for waxing a few hours later. The oil level was down to the low line on the stick so I topped it up with Mobile One 15W50. During the next 48 hours I moved the car around a couple of times as I waxed it and each time it sounded like a sewing machine at idle. I had hoped to get out for a run Monday afternoon for a run but it was constantly raining and between the fresh wax and the victoracers I decided not to. The weather was similar on Tuesday but I started it up, let it warm up then ran it up to 6000 rpm. The lifter have been quiet since. The weather cleared and we went for a 20 mile drive today. All has been fine since revving it up.

So my question is "do you think the clicking sound is a symptom of the lifters being damaged"?

mike_hammond

Not really Bruce more like its been standing and it needed a bit of gas to pump them back up again, I wouldn't worry unduly unless it becomes an everyday occurance.

Mike

BruceWard

Ok, you caught me. I should have said that I only drive once or twice a week.

I am going to keep watch and make sure I top it up each time the oil level drops to half way between the marks.

Also it may be relevant, the 968 currently had 59.5K miles on it.

flash968

sounds like you just have a lazy one - back when i was doing american stuff, when we had one like that, we would either use a motor flush or, when times were tough, a quart of tranny fluid - then we would run it for a few minutes and then change the oil - cleaned it right up and all was well again

no idea if that can be done on these motors or not

thoughts anyone?

BruceWard

I think Mike hit it, it had been a while since the car had been driven and the clicking was only at idle. The oil had sunk down out of the lifters and needed to be pushed back up there. Revving it to 6K rpm made it quiet again. I took it out for another drive this evening and it is running great!

I mainly posted this to document how I got rid of some lifter noise, and to ask if anyone thinks lifter noise at idle is anything to worry about.

RajDatta

Bruce, you are spot on. Some of them are losing oil when sitting. They get pressurized upon startup and you are good to go.
Also remember 15W50 is thicker, so it takes a tad bit longer to get everywhere. A 5W30 would get rid of the lifter noise sooner.
Raj

BruceWard

Any thoughts on 0W40 vs 15W50? The temperature here ranges from low 30s F in the winter to over 100 F in the summer. I do not drive much during the cold time, but am likely to be at an AutoX when it is 100+ with a heat index of over 120!

Everything is fine now, perhaps I should just drive more!

Here is the manufacturer info

http://www.mobil.com/USA-English/Lub...bil1_0W-40.asp

http://www.mobil.com/USA-English/Lub...il1_15W-50.asp

Jay Wellwood

If this were on a 928 I would say that it sounds like the oil check valve in the heads is leaking by - probably abit dirty and need to be taken out and cleaned.

Haven't looked at the 968 manuals to determine if the same exists....but I'd wager that it does.

Jason Judd

Bruce,

I would stick with the 15/50 if I were you. I live jsut outside of NYC and have never had a problem during the cold months.

If you ever track the car, I would even more strongly suggest the 15/50 grade.

Jason Judd

RajDatta

I agree myself that 15W50 would be the better oil to use for our cars. But the fact that you changed your oil weight and recently started to get lifter noise at startup are somewhat related.
I think you just answered your question, drive your car more often .
Jay, we have a oil pressure relief valve in our cars. Not sure if thats what you are talking about.
Raj

mike_hammond

I think Jay is refering to the check valve, bottom left corner of the head looking from the top above the exhaust manifold. Wouldn't have said its that in this scenario given it was a one off occurance.

Another theory could be the recent oil change dislodged some crud which could have temporarily blocked one of the lifters. My car has been run happily on 0w oil since new, but I have recently upped the weight to a 15w50 as the old girl has got a few miles under her belt now and I do take it on trackday events so a little extra protection is required even if it does sap the HP slightly

Mike

flash968

bruce - on the subject of oil viscosity choice, consult dave greimann - he's the oil guru - he has posted some pretty specific stuff over on 968.net for different temp regions and such, with great explanations of each choice

Jay Wellwood

Exactly what I was referring to Mike.

I know of at least 1 928 that had one of these things get dirty if you will and each time he started the car up the lifters rattled for abit until the oil pressure came up. Shutdown the engine opvernight and the oil would drain back to the sump only to repeat the process the next morning.

Just a thought...