Well, I recently put in a SOS supercharger and made the mistake of putting Mobil 1 in for the first fill. It seems to be cleaning the engine well (turned dark FAST) but sometimes it seems to be gulping oil, sometimes not.

Oil usage around town seems to be pretty normal really (for M1 anyway). Since I've had it on since the beginning of May I've added about 1qt and that was like 5+ gas tanks. High usage, but not real high for Mobil1...appears to be less than 1qt/1K. I had Mobil Dino oil before the SC and it didn't gulp that in any significant quantity (I may have used the rest of a 1qt bottle in the 4K or so I went on my last interval).

Anyway, I seem to have a fairly significant difference in readings at different times...sometimes under the same circumstances it is up to 0.3qts different.

It DOES seem to be using oil on the highway though. Perhaps a PCV valve issue...so I have a new one on order. It rattles a little when shaken side to side, but not vertically. I think on the highway, depending on how I drive, I'm probably under positive crank pressure more often than someone NA.

So, last week...250 mile trip. Stick was down 0.9...but engine was just turned off so it was hot and not fully dripped into the pan. When I originally filled that tank, I was down about 0.5, but on a cold reading. So, I was "OMG 0.4 qts in 250miles...that's like 1.6qt/1K!! I understand there's some thermal expansion when the engine is hot, and it seems to add around 0.2-0.3.

Last week, I started to really start looking into it. Before this week's trip, I took a cold reading...down 0.3qt. After going 200 miles highway, took a cold reading again...down 0.7. Then I remembered I was on an incline ...down 0.5qt when I got the car leveled (0.2qt/200 miles). So, I added 0.4qt at the next fillup to bring me to -0.1 (that's all I had). Now, another 200 mile highway trip, and this morning, cold reading, level, I'm +0.1qt...like I gained oil on a highway trip.

The supercharger itself is oil fed, and seems to be inconsistent in how it drains. I think the capacity with the blower is a little over 6qts, but my readings are not consistent, even when level and cold. It's like sometimes maybe the SC drains more oil into the pan than other times. It's making my oil usage analysis difficult.

Needless to say, I'll be going with something other than Mobil1 due to the usage, but anything in this seem alarming? I don't see white smoke or anything like that. I fiddled with the PCV valve a little before my last trip...shook the crap out of it. I don't have comp test results, but my dynos are quite strong, so it appears the block is quite healthy.

 

Use Amsoil, best oil hands down.

 

I always check my oil in the exact same place, and always after letting the engine sit for 10-15 min after being fully warmed up. My readings are pretty consistent. Any deviation from the normal routine and I get inconsistent readings.

Sounds like you're taking readings in lots of different places and with different states of engine temperature and time since being turned off. (I know that's unavoidable sometimes since you can't always check in your garage/parking spot/whatever if you're traveling)

Also, I never fill it 100% to the full mark, just in case my reading that day did happen to be inaccurate. Don't want to accidentally overfill.

 

I always check mine when cold, fill it up to one X below max. No matter how hot it gets later, its never overfilled and i always get consistent reading. I also make sure to check it at least 3x at once.