Installed mine 1400 miles ago. Bought the one with the test port. Seems to be a high qualty product and easy install. No oil test samples yet although I did do a sample before putting the system on to get a baseline figure. That oil had 4k on it so I am waiting for the 4k to roll around again to see what difference the bypass may have made. Could not find any downfalls with the Oilguard.
Dave