V12 breathers revisited.

[alan-ix350]

Can anyone explain why the PCV valves get blamed for letting oil up to the throttle bodies
These valves are just a one way valve to stop any blowback not to restrict oil /fumes so cant see how replacing them would fix anything
Seems to me the oil separators are the issue so as they are inaccessible, a catch can in line before the throttle bodies will suffice

[DB9VolanteDriver]

The PCV valves are not quite as simple as one-way valves. They restrict flow with a variable position valve as a function of the delta pressure across the valve to account for different running conditions. When they work as intended, everything is OK, but they tend to get easily gummed up from the oil vapor and cease to function. But you are correct that the root of the problem is a lousy separator system.

Replacing the PCVs once a year would not be a problem if they were located near the throttle bodies, but they aren't. So, either install a couple of catchcans or relocate the PCVs. Either way you've got some initial work to do.

[alan-ix350]

Thanks Steve, catch cans it is then

[gaussianmist]

None for the DB9??

[crispyj]

I had the same issue , when I purchased my car the first thing I did was change the air filters. On removal they were sodden with a lot of oil.

My car had covered 79000 miles at this point. I changed the filters and after speaking with opie oils on what oil to use in my higher mileage car they suggested running motul sport 5w40.

Since then I have had no oil contamination on my filters, so I believe running a slightly thicker oil has helped dramatically.