I’ve had my 12 valve 3500 for about a year now. LOVE IT! The truck is dry dry dry as a bone underneath. Just the last week or so the truck is dripping oil from the breather tube when I park it. I checked the oil after a couple months and it was 2 quarts low. I have done some medium trailer hauling the last two weeks but nothing crazy..

Any thoughts??

 

Before you get worried the motor is tired and has lots of blow by.
Check for vacuum leaks. As our vacuum pump will dump that air into the timing cover is there is a leak it is sucking in.

 

Did you change brands of oil? Some oils will cause that problem. As oliver said vacuum leaks cause it too.

 

I put Rotella T4 in when I first got the truck. I read on the forum you can test your vacuum by turning on the AC and switching from defrost to vent to floor. They all switched fine. I had a vacuum tub cut when I first gotthe truck but I repaired in months ago. The leak just started a couple weeks ago. Thanks for the reply

 

Just because the vents still change does not mean you do not have a leak, just not.a big enough one to completely over power the vacuum system.

 

Rotilla was one oil that produced blowby on my truck.

 

What would be the better test for vacuum leak?

What oil is the best to reduce blowby?????????

 

I just run Tractor Supply oil. Works fine. I think it was Traveler brand 5 gal.

Vacuum leak: Get a vacuum gauge, 1/8 in T and short 1/8 hose. Put T in where the A/C supply connects under hood. Check Vacuum running, shut down and monitor gauge. If it drops fast you have a leak. Also change functions on A/C and repeat because it may be a diaphragm.