Oil consumption

[Sveedy]

So over the last couple of months I have noticed a sharp increase in oil consumption. Like apx 1qt per 1000 miles !
This is a totally rebuilt engine with about 30k on it. No noise or ticks. No wet spots on the garage floor, and no smoke that I can see when starting up or driving.
The only thing that has changed is that I had to use Mobil 1 0-40 for the last oil change. Previously I had been able to find 10 or 15-40w.
Not so easy now for some reason. I'm going to have my son follow me on the highway and see if any smoke at all is coming out of the tail pipe, but short of that, any ideas where my oil is going ? I was thinking maybe the turbo ( it too has been rebuilt ), but if it had a leak, I would think I'd see smoke. The oil just seems to disappear.
Thoughts ...?

[454cid]

Mine has gone up too over the last year, too. I've got an original engine with about 120K miles on it. RobertDIY told me that it was likely valve stem seals.... or at least that's what I think he was telling me. Any chance yours would be bad after 30K miles? Who did the head work?

I run 5w40 but I can't recall exactly which oil I used. It's either Rotella T6, Valvoline synthetic European formula, or it could also be Valvoline Premium Blue Synthetic. It's got random others in it now, since I keep having to add oil.

[scot850]

Running a 0 weight oil on these engines is not a good idea. I appreciate 5W-40 which I use as specified for my 2000 V70R for where I live does not burn anywhere like that.

I would suggest trying Walmart or Amazon or Rock Auto for oil of the correct type and see if that helps the consumption. As long as I have worked and owned cars, adding a thicker oil to an old engine was the way to go when oil consumption increased.

Neil.

[Clemens]

While I've been a fan of Mobil 0W-40 for many years in other cars, I had the same problem once I switched my 96R to 0W-40. On the 94T5, it would leak oil through all possible seals, even with a freshly cleaned PVC.
Switching back to 5W or 10W solved the problem. In my 96R, I'm running 5W-50 at the moment.

[BlackBart]

Just that much difference in viscosity? Interesting. My old Alfa gets 20-50.

[Sveedy]

Well I'm wondering if the lower viscosity oil isn't playing well with the turbo. Knowing how hot the turbo can get, particularly when it's really spooled up, maybe the thin oil is basically vaporizing as soon as it hits the hot bearings etc inside of the turbo. That little bit might never show up at the tail pipe. Just a theory....

[BlackBart]

Have you tried someone behind you at full throttle? Then sudden off-throttle decel down a hill?

[Sveedy]

No, I haven't had anyone follow me yet. But I switched MAP's to a lower boost one, so I'll see in apx 1k if anything has changed one way or the other.