Re: Bypass vs. full flow oil filters

Posted by Tim Cole On 2012/6/5 18:37:16

Given the request for comments, I'll throw my two cents in.

Today's highest cost prime movers use full flow plus bypass. The bypass is a multi-stage filter. They also use pre-cleaners in addition to primary and second stage air filtration.

If you can find a good engineering library you can check out editions of the "Handbook of Petroleum Engineering". They contain filtration studies some of which concluded that diesel locomotives were ruined after three months without filtration.

For these Packards there are a couple of very important considerations.

One is that when these cars sit parked for more than a week the settlement effect is virtually the same as full flow filtration. When they sit for a month the results are way down in the microns.

Secondly, the floating pick up is very effective. Modern cars don't have floating pick ups any more because of full flow filters.

After that the air filter is actually more important than the oil filter. And that is according to the Packard company. I remember an old timer who fitted an oversized paper filter to his original 902 and it ran for years and years without a rebuild. For any car without the optional oil bath cleaner I would follow his lead.

Finally, emission controls and unleaded gas have cleaned up the crankcase which is why modern engines run so long without blowing up. In fact, motor builders have to engineer failure into modern engines so that they have to be replaced. A million miles on an engine is entirely possible given changes in the computer program cells and sturdier parts.