1. Adding gasoline in the older benz diesels was approved in cold weather when no winter blend was available. I wouldn't recommend it in warm weather.
2. Adding motor oil if its clean would be ok.
3. Hitting the rev limiter every shift is not a terrible thing but its useless as it really does not improve the acceleration over shifting at about 80% of the max rpm.
4. Revviing it in neutral is silly but not horrible. I would not do it.
5. I don't know what is causing the sparks but they don't seem like a good thing.
6. Diesels imho do not need anything done to blow out the carbon if they get driven on the highway on a regular basis and are in good running condition.
7. Cervan is certainly likable but has some unusual ideas.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.