jonule wrote:Only, there is a small problem for motorists who own old vehicles: the valves of old vehicles wear out (back to the problem before 1930). And additives that have replaced lead tend to attack the joints and rubbers of older cars. The problem is even more acute in 2 engines time (motorcycles, cyclos, lawnmowers etc). But the SP98 is suitable for the majority of relatively new cars (roughly from 1985). In 2000, definitive end of the super leaded which leaves room for a new SP 98 modified because lightened in toluene and benzene. Fortunately because otherwise it was the end of the engine 2 time whose crankshaft seals did not support these additives (it creates an air intake at the pump housing and therefore clamping primers).
* The uncatalyzed ones have always been designed for super leaded which was replaced in 2000 by 98 SP to which it is necessary to add a dose of "valve anti-recession" additive at least every two full. The additive can only be used on vehicles with special valves and seats (from around 1985).
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For the wear of valves and seats, it depends on the manufacturers: for example we can use the SP98 on the Citroën DS without accelerated wear problems from 1969 (on engines in good condition and by replacing all the hoses and old polymer joints).
Indeed at the beginning the SP98 contained up to 30% benzene (the record was in the brand ARAL), this product is indeed a waste for the oil industry because nobody wants, but it is a excellent anti-explosive and a powerful solvent (toxic) ...
2-stroke: on an engine that has been running on lead for a long time, this could indeed cause damage, detachment of deposits, tearing of the lips of the oil seals, etc ..., not on a new engine using at least oil semi-synthetic of a good brand (Motul) at 2%: the ulm with 2-stroke engines which are pushed to maximum power for 5 minutes or even more on the initial climb worked very well with (some who did not take their precautions got into trouble level pipes (there is one which had an engine shutdown in flight following the rupture of a "tricoclair" type PVC pipe, this material being totally unsuitable (hardens and breaks) for use with petroleum products not only unleaded gasoline !!!), also plastic carburetor float, etc ...) ... Otherwise the old leaded 97 was rather a poison for the 2 times because it clogged the engines due to deposits of lead especially in the fire segment grooves