"Bruce Bergman" > > And the reason it makes sense to use a bypass filter and do a > periodic oil analysis on large engines (rather than simply change the > oil on a time/mileage basis alone) is because large truck engines take > 3 to 10 gallons of motor oil to do a change. That may be one reason. The sump of a large engine is no more than a small engine in relation to its cubic capacity or torque output and the cost of the oil fill is no more important. The main reason for longer drain intervals using SHPD oils in conjunction with analysis is to keep the vehicles out of the workshop and on the road. In other words it is to lower the running cost of the fleet. > The cost of having the oil analysis done has to be significantly > cheaper than the materials and labor cost to change the oil. It makes > sense for large engines like the above, but the average car or light > truck takes only 4 to 5 quarts of oil - having the oil changed is far > cheaper than the analysis. Even with synthetic oils it's a wash. With only a small fleet I tend to agree that very extended drain intervals are not economic due to the benefits being outweighed by the cost of administration. Drain intervals can safely be extended by a factor of two or three by using a long drain oil combined with a regular filter change. The trick is not to push the limits of either the oil or filtration. If the manufacturers recomendation is for a change at x miles with a normal humdrum oil then a dino 228.3 [45,000km] oil should be safe to x times two miles while keeping the filter change as normal. If a 228.5 synthetic is used then perhaps three times normal interval can be tried. In each case an analysis of the oil would be done once only at the end of the period to confirm the safety of the interval. Just my opinion and what experience has taught me is sensible. Note that my experience is with diesels and that I would not take an indirect injection diesel much further than 10,000 miles between dumps whatever the oil used. Huw > > With my LandCruiser paying for an oil analysis might make sense, the > 'F' motor takes 8.5 quarts of Mobil1 at about $36, versus $40 for the > oil analysis - but they're just going to tell me to change the oil > every 2nd or 3rd time anyways, so why bother... ;-) > > --<< Bruce >>-- > -- > Bruce L. Bergman Return to Main Index
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