I'm kinda new to the BITOG forums. Some contributors have dismissed the people that claim that the reduction of ZDDP is bad for flat tappet engines. Some have said that the new oil has other anti-wear additives that make them better than the old oils. They seem to follow the oil companies like they can do no wrong. It seems to me that the reason the ZDDP was reduced, in the SM oils, is so the catalytic converters, in the new cars, would last as long as the 100,000 mile warranty. When I look at the VOA's for oils I see a lot of calcium, which I think is part of the detergent. A lot of zinc and phosphorus that I think are in the anti-wear additive ZDDP. A little molybdenum and a little boron. It seems to me that the only thing that has changed very much is the reduction of zinc and phosphorus. What is the substance that has been added to make up for the reduction of ZDDP. What ever it is should show up in the oil analysis. I guess the SM oil is good enough for the new cars but I don't think they are necessarily good for old cars. My two modern cars will get SM Mobil 1 because think it is best for them. My two old cars are going to get something with more zinc and phosphorus. For those of you with old cars, Texas Refining Corp. has a diesel engine oil called Pro Spec III in 15w40. It is a CI-4, SL oil with 1400 ppm zinc, 1200 ppm phosphorus, and 4400 ppm calcium. It has a 15 plus TBN. This stuff would be poison for the catalytic converter in your modern car but your 50's and 60's cars will love it. I don't work for these guys; I get my TRC oil at the local CO-OP farm supply store for $3.50 a quart.