We had a fellow on another automotive forum some twelve years ago hawking a brand of motor oil he represented as an MLM dealer who claimed it NEVER needed changing. "Only change the filter and top off the oil", was his claim. Now back as late as the early thirties that could be done successfully on high-mileage vehicles where the heat boiled off liquid contaminants and the filters could trap the big chunks.
One engineering professor of the era swore by this technique, because in essence, your oil got better the more it was subjected to heat and filtration . . . which is probably more a commentary on the miserable state of the product in those days than the no-change technique. Dad proved it on the highway as the supervisor of a large electrical utility district in Western Kansas. It wasn't unusual to drive his fleet car 60-70,000 miles a year without a full change of oil.
But there were several circumstances then that allowed that. First oil back then was
just a lubricant - no additives. Second, engines of the day were lowly-stressed, and made few demands on the lubrication system. Third, ordinary cars of the era didn't last that long anyway, wearing out an engine was unlikely because something
else major fell apart long before the motor. Trying that stunt with a high-detergent SAE certified lubricant in a modern high-compression engine was mechanical suicide.
Our oil dealer friend insisted HIS employer's product was different, in fact they not only endorsed never changing the oil, his company would permanently warranty the engine against lubrication failure. Fast forward a year or so, and we'd had an earful of this "permanent" motor oil. No one on the forum believed it for an instant, and privately everyone was laughing at him. Then one day at around 24,000 miles, his engine seized. Ruh-roh.
His car was a Lexus RX300 - that in the first and second model years of production (1999-2000) had undersized oil galleries in the head that could sludge up with cheap oil and long change intervals. The solution was to run synthetic oil and change it every 5K miles (as recommended by the oil companies at the time). Those of us who were reasonably careful never experienced the slightest sludging - By 2002, the head was redesigned and engines from that model year onward never had a problem with the Toyota-designed V6.
Naturally, Oil Boy went to his Lexus dealer, screaming for warranty replacement when the motor ran all its bearings and locked up. They pulled his file (they
do keep meticulous service records and provided all service free for the first 2 years), and there was NO record of an oil change. They pulled oil samples and checked the drain plug and filter. Whaddya know? The oil had never been changed - except to replace the break-in oil at 5,000 miles with his own "moose milk". Lexus shrugged and apologized, but they couldn't help him. So then he went pounding on the door of the MLM oil company to get them to honor the warranty
they offered. As you might expect they said, "
What warranty?"
Lexus did offer to replace his engine at minimal cost, if he would buy the part. The
1MZ-FE engine, voted one of Ward's 10 Best, was a
little expensive, in the neighborhood of $14K for the crate motor. Oil Boy screamed bloody murder at the news, called everyone he dealt with unmentionable names, and retreated from the forum permanently. I recall one or two of his friends left behind remarked that he eventually had the dealer replace the engine . . . he was WAY upside down on the car and he couldn't afford to continue payments for something that just sat in his garage, immobile.
Moral: Gas or diesel, change your oil and perform ALL recommended service at the intervals indicated by the manufacturer . . . unless you don't
want a warranty.