Project Viper GTS: Part 8 – Bob’s Air-Oil Separator

Viper Oil Accumulation after 1000 miles from Valve Covers and PCV/CCV The oil from the Valve Cover (left) would have been enough to saturate the airbox sponge and we likely would have seen traces of oil at the throttle body again.  But look at the amount of oil the CCV (right) was pumping into our intake manifold.  We had no way of knowing this much oil was being ingested by our motor.

Initially we thought the biggest issue was oil being sucked in to the engine from the Valve Covers since we could easily see signs of it, but from our testing it was what we couldn’t see, the Crank Case Vent, which was pumping the most oil into our combustion chambers.  Overall we were extremely satisfied with the performance of the Bob’s Auto Sports AOS and the decision to use it for the PCV/CCV rather than for catching oil coming out of the valve cover.  We feel this is a MUST-have for any Viper owner to catch unwanted oil from being sucked into their engine, especially supercharged cars and those that will see track time.

While not as important and a secondary issue to the CCV, it’s still worthwhile to address the Valve Cover oil and we will continue to utilize the RareFab fabricated catch can, but will add the high quality ball-valve from Bob’s onto it for easier serviceability. You can probably drain the Valve Cover vent as frequently as oil changes while the CCV should be drained at every 2,000 miles.

To build your own Viper-specific AOS kit, you will need:


Crank Case Vent Kit:

– Bob’s Auto Sports Universal Oil Separator Kit – with Standad Bracket

– McMaster Carr – High-Temperature Silicone Rubber Tubing – Semisoft, 3/8” ID, 5/8” OD, Opaque Black

 Part #:   51135K36 (10 ft length).  Cut to 23.5” & 24.5”

– McMaster Carr – Brass barbed Hose Fitting, Adapter for 3/8” Hose ID x 3/8” NPTF Male Pipe

Part #:   5346K19 (pack of 5)


Valve Cover Catch Can:

– Catch can.  You can use a Bob’s Universal Oil Separator Kit – with standard bracket and a 5/8” brass fitting

– McMaster Carr – Brass Barbed Hose Fitting, 90 Degree Elbow for 5/8” Hose ID

Part #:  91355K55 (pack of 1)

– McMaster Carr – High-Temperature Silicone Rubber Tubing – Semisoft, 5/8” ID, 7/8” OD, Opaque Black

 Part #:   5113K52 (2 ft length) X4 (8 ft total)

No matter what car you drive, the Bob’s Auto Sports Oil Separator is a quality product that successfully removes the oil from the Crank Case Vent as well as from the Valve Covers.  From our own testing, 5.0L Coyote powered Ford Mustangs pump a lot of oil from the valve covers into the intake manifold and greatly benefit from using oil separators.

Stay tuned for future Project Viper GTS articles.


Bob’s Auto Sports



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