JLT Oil Separator, why you may want one. But before we go there, a word on crankcase ventilation.

Blow-by is combustion material blowing past the piston rings and into the crankcase. If not ventilated, this material condenses and mixes with the oil vapor, forming sludge and diluting the oil with unburnt fuel. Thus it becomes necessary to ventilate the crankcase.

Earlier engines let blow-by products leak through gaskets and seals. Not cool.

Later came the draught tube, a pipe running from the valve cover down into the slip-stream of a moving vehicle that created a draft that sucked the vapors out of the crankcase. A breather cap in the valve cover supplied the air for ventilation and prevented negative pressure in the crankcase.

Today we use a PCV system, Positive Crankcase Ventilation.

By utilizing the intake manifold vacuum, crankcase vapor is drawn through a breather into the crankcase through a PCV valve that acts as a flame arrester and regulates the flow of combustion byproducts back into the intake, carrying with it oil vapor.

Filtering consists of a fine mesh stainless steel screen that traps fine oil vapors and releases them once heavy enough to fall. Photo from JLT

Oil vapor back into the intake can cause carbon buildup on the intake valves and coat blower rotors and intercooler fins in addition to lowering the octane level.

To help prevent this, install an oil separator, also called an oil catch can. It’s a simple, less than a thirty-minute job for any reasonably capable DIY’er, discounting any possible project creep.

JLT oil separators use a fine mesh stainless filter screwed on top of a three-ounce canister. This, placed in line with the PCV hose, separates oil from the crankcase vapors.

As a reminder, make cleaning the oil separator a part of every oil change.

Please, dispose of the oil in an environmentally friendly way. Photo from JLT

My Mustang has one. It traps about a teaspoon of oil around 2000 high-revving miles. That doesn’t seem like a lot, but when it comes to performance, every little bit helps. And I like a clean engine, inside and out.

I installed a JLT oil separator on my easy-going Tacoma. So far, the container is clean as a whistle, but that’s expected under average driving conditions for most vehicles. What happens on a hard-hitting 3000-mile road trip towing a 4000-pound RV? I don’t know yet. But, I’ll post the results in a comment below afterward.

Oil separators are not CARB certified.

Learn more here: https://www.jlttruecoldair.com/oil-separators/

2 thoughts on “JLT Oil Separator

  1. I remember working on cars, since 1964 and have seen a lot of changes to the internal devices that control each system. The filtering means has reached quite a level of precision, including that 2 tsp that you mention, Peter. Also remember taking the air filter housing off and putting a screwdriver at the butterfly flap, then I could rev the engine, replace the housing and be on my way. First vehicle: a 1963 Corvair. It got much negative attention, but I experienced only minor problems. Thanks for the video, too. Quite informative.

    Liked by 1 person

    1. Those were the days, eh? Well, not really. Working on cars back then was for fun and necessity, and there wasn’t anything I wouldn’t tackle. Now it’s tinkering and polishing. I had a Corvair, too. I’m not sure of the chronology, but somewhere near the beginning. Mine never ran. I bought it for a song, hoping to fix it and have something to drive. I failed. However, I thought they were cool, sporty. Had mine only ran.


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