Clogged PCV

[Steve_RI]

I just repaired a rather mucked up PCV system on my 2002 VW 1.8T (77K). The oil was very clean on the dipstick at the time due to a recent change, and I noticed that the oil got progressively darker over the next couple days. It's black now. Is there a correlation/explanation? Regardless, the Auto-rx is on the way.

 

[TexasHonda]

I doubt there is a correlation. However, a blocked PCV would probably increase crankcase pressure, reducing blowby from combustion passing the pistons. Conversely, when you fixed the PCV system, the crankcase pressure should be reduced and blowby might increase, leading to more rapid oil darkening. This is normal and indicates the oil is suspending particles as intended.

I've noticed that Toyota vehicles seem to have cleaner oil, that stays clean long after an oil change. Anecdotal observation based on small observation set (2 - 97 Avalon and 01 Celica).

good luck

 

[Quest]

IMHO nope. A clogged PCV valve should accelerate the deterioriation of your motor oil due to poor/inability of blowby and moisture evacuation.

A good PCV valve shall helps in keeping your motor oil cleaner, lasts longer too.

 

[Steve_RI]

I see, that makes sense. Incidentally, it was a leaking valve cover gasket that clued me in to something wrong.

 

[m2200b]

I'd go with the reduced blowby , additional head deposits
if for longer periods. I'd probably do techron too.

 

[Quest]

To be honest with you, I don't gauge the oil's condition by merely eyeballing the colour of it.

When in doubt, I always change out the oil even if I have some decent dino oil around (5W30 formula shell or Castrol GTX). I know it sounds like a waste but I would rather waste one round of "questionable" lubricant and then start from mile "zero" again than simply eyeballing some questionable oil and assume that it's still good to use.

That's only me though.YMMV

p.s. plse service your PCV valve on a regular basis and ensure that nothing along the way is clogged.