seattle951

Why would the valve train not like it? I purchased my 924S with a 140,000 miles and drove it to 200,000 miles before I had to sell it to make room for a BMW. I went through a head gasket and oil cooler seal and did the timing belts twice. The mechanic never reported any issues with the value train. It purred like a kitten when I sold it.

I used Mobil 1, 0W-40 almost the entire time. After reading on Clark's Garage that the car should have 20W-50, I tried it. The car was not happy and I changed the oil back after about a week. (It cranked slowly, had oil pressure alarms when cold and felt constrained.)

You might be right about the oil being hard on the valve train, but it was not my experience. What am I missing?

raleighBahn

Out of box thought as you requested: you are only using your car for short, infrequent trips when cold. Water has built up in the oil as a result of not getting hot enough, and the accumulated water is freezing when the temps dip. Your recent oil change eliminates the problem, but perhaps will happen again as water builds up?

I have an oil temp gauge and am surprised by how far i have to drive before the oil temperature gets to operating temp, especially with thicker oil.

mahoney944

I've never noticed any mixing of fluids but its something to think about.

raleighBahn

I could definitely be wrong, but my understanding is that oil has to get above the boiling point of water to get rid of naturally occuring water vapor produced by the engine.

The hypothesis does have the quality of explaining your situation when temps are cold as opposed to warm. If true, it means that an oil change to any viscosity (even the same), would have temporarily solved the problem.

Another angle, same line of thought. .. do you keep your gas tank near full? If near empty, you could get water condensing in the empty space, which then freezes. I am reminded of you heating your car before it will start by the germans having to burn fires under their tanks in russia to get them started (fuel freezing, oil too viscous).

Alan 91 C2

Actually, the oil temp will boil off the water at 100+ degrees. The partial pressure of the water vapor will exceed the ambient H2O vapor pressure. Just like water on a floor dissipates into the air, without boiling. But it does take a little time, say 10 or 15 minutes of warm temps.

Now the water in gas takes a little longer, based on the volume of gas, and surface area of the gas tank in cold weather. There it is best to keep the tank full and prevent the water vapor entering.

mahoney944

I'm a few days in on my new 10-40 oil. No issues so far...had some cold days as low as 26 degrees and some warmer 40+ days. No starting issues so far. I'm gonna start it tomorrow, 2 days sitting without start on a chilly morning. So well see and I'll report back. Definitely not enough proof to call it solved but I'm seeing promising results

jej3

PM sent to Mahoney944. Curious if this cured all the issues he was posting about.

mahoney944

Updating an old thread: here's the solution

As it turns out the solution consists of two parts.

1. Make sure your speed and reference sensor bracket is the updated one. Which uses a sleeve to shield the signals. https://944online.com/index.php/refe...block-kit.html

2. And most importantly, the factory starters are known for interference issues. Most rebuilt " auto store replacements" suffer from this even more. Update the starter to this and you'll be good.
https://www.pelicanparts.com/More_In...RoCthkQAvD_BwE These are high torque starters which are 20 years of advancement in starter technology. Worth every cent. Started the car today in 18°F fired right up after sitting for a month.

Though not a needed solution for starting. I also now use a solid state dme relay with pump prime. This primes the fuel system for 3 seconds before starting the car. Definitely improves starting after long sits. http://www.ftech9.com/new-products/993-ssr-pp