[Vwdiesel] Gas vs diesel hybrid

[William J Toensing]

I could & hope I am wrong, but I think gas engine hybrids are better than diesels under the normal conditions most cars are exposed to, namely short start & stop driving, based on my experience around 25 years ago. My first diesel was a 1979 Rabbit, which was bought new, but went to my X wife in a divorce. It had around 30,000 miles on it when this happened. My second diesel was a 1983 Nissan Sentra diesel which had about 51,000 miles on it when I sold it & at that time I suspected the head gasket was leaking as evidenced by a black scum in heater expansion tank, running warmer than normal, & periodically having to add water to the cooling system. My next diesel was a 1985 Mazda 626. At 50,000 miles the head gasket blew leaving clouds of black smoke behind. Mazda paid for the repairs under the Calif. emissions warranty, then 10 years or 100,000 miles. At 70,000 miles, the head gasket  blew again, this time, causing overheating. Because I was using synthetic oil, the engine did not seize but got so hot the valve springs lost their temper & the engine stopped. However, the engine got so hot, the temper in the block was destroyed & the engine had to be replaced. This time, because of the mileage, I had to pay 50% of the engine replacement & Mazda paid the other half because only 20,000 miles elapsed between the first head gasket replacement. I also found out the Mazda used stretch bolts which Mazda did not recommend re torque. However, this time I had the head re torqued & the engine lasted another 127,000 miles when it overheated because a thermostat hose blew because I did not replace it along with other hoses, because I didn't know it was there. 
I have had a long term interest in diesels ever since I saw my first Mercedes Benz diesel back in the early '60s. When GM came out with the converted gas to diesel Olds 350, the engine that gave diesel a bad name in the USA, I would ask owners of these GM diesels what their experience was. I found a pattern that when the engine was used for mostly local driving with occasional trips, the head gaskets would blow  at around 20,000 miles. The weakness, I understand, was due to only 4 head bolts per cylinder. That frequent heating & cooling along with the high diesel compression, would cause the head bolts to stretch, causing eventual head gasket failure. However, I found a few Olds GM 350 diesel owners that were claiming 250,000 to 300,000 miles on these engines with no problems. However, the response I got from those owners was they would drive these cars from 75 to 300 mile trips for most part rather than trips of 10 miles or less.
Since a hybrid engine frequently cycles off & on, I wonder, based on the above, how well a diesel engine would do in this environment?