Re: Shudder when letting out clutch in 1st

Posted by Mark Buckley On 2015/1/7 23:32:13

I'm probably going to catch a lot of flak over this, but here goes:

I had the same problem. I asked my mechanic to troubleshoot the issue and he couldn't find an obvious problem. He's a good mechanic--his daily driver is a 1939 Dodge--and his diagnoses are usually correct.

He asked me what type of motor oil I was using and I told him, Shell Rotella.

He told me that was the problem. He said that modern oils are manufactured to have small, short-chain molecules. These small molecules are inappropriate for older cars, he said, because they can get past and through seals. This causes the clutch to slip and shudder when you let up on the pedal while the car is standing still.

He suggested I replace the Rotella with Chevron Delo 100. The Chevron oil is still available in some markets where older Detroit Diesel engines are in use. Delo 100 is essentially an obsolete oil that only goes in obsolete engines.

I did as he suggested and was pleasantly surprised. It took about 4-5 months for the shuddering to stop, and it hasn't gone away completely, but the performance is WAY better today than it was when I was using the Rotella.

My 1950 is a daily driver and I'm guessing I had to put 2-3,000 miles on it for the shuddering to get to where it is now. I've put 5-6,000 miles on the car using the Delo 100 and have not noticed any negative effects.