Erratic oil dipstick readings.
 

I know this topic has been brought up in the past but over the past few days I’ve did some tests and I’m still scratching my head....

I regularly check my oil, think I have OCD :) in the past I’ve noticed some odd behavior with oil readings. I know you should wait an hour or 2 to get accurate results. I actually spoke to the lead tech at my GM dealer and he says it’s best to wait 15-30 mins after shutoff for accurate results.

So here is what I noticed recently...

Few days before the snow here in NJ went for a drive, came back put car in the garage. About 15 minutes later i checked the oil And it was about 1/2 way up on the cross hatch (I like to keep it about 3/4 on the cross hatch) I waited about another 15-20 mins and the oil came up right about 3/4 on the hatch.

Did some cleaning on the car and some other odds and ends over the next 2 hours, checked it 2 more times and both times it was in the same spot. Great. Closed hood. Done.

Today, decided to go for a quick drive, checked the oil before starting and it was 1/4 up on the bottom of the cross hatch.... the car didn’t move prior, sat in same level Spot for days in garage, however it’s been cold.

I didn’t touch the oil, went out for my drive. Came back parked in same spot, check oil after 20 mins and oil was back up 3/4 on the dipstick. Left it for an hour, checked it again ... still same ...

I don’t get it, it’s like some sort of witchcraft going on.... lol like the oil when cold is settling lower. I really don’t get it? But has anyone else noticed anything similar?

I remember last year I thought it was low, so I added more to
Bring it up and pretty much did what I did here and ended up overfilling it (or so I thought). As it was over the cross hatch after starting and letting sit an hour.

Thanks

Well did a quick search on synthetics and physics of oil, apparently in cold weather, especially sitting for days oil will contract and when warm it of course expands.

I guess it’s best to check as suggested with engine warm after an hour or 2. Or when cold, but not below freezing for days as results will differ, especially having 10 quarts of oil.

Oil reading on this car is very random--never seen that on any other car. My advice is to only check oil in the morning, 15-20 minutes (like dealer said) will definitely not return accurate results. You need to wait at least 1+ hours.

The weirdest thing I see is that after a change to fresh oil for track events, my car burns ZERO oil after 2 days at the track of 3-4 sessions/day of hard driving on a very demanding track like Auto Club Speedway, with frequent long runs over 150 down the front straight and other high speed straights--I'm doing laps in the top 10. This includes two 1-hour drives per day back and forth to the track from my house in LA to Fontana. I check the car the next day and oil level is still not a hair lower than when it was filled 2 days prior to the track event.

Fast forward a couple of months and maybe 1000 miles street driving on same oil after an event like this, and my car seems to consume some oil at random intervals from casual canyon drives in LA hills or around town--maybe none for a few hundred miles or maybe 1/8 quart.

Are you in full-auto on the track, but using paddles on the streets and canyons?

2018 ZLE, so 6 speed everywhere. Maybe my car is telling me it prefers to be on the track at WOT :-)

I have never had a problem reading the dipstick in my ZL1 or 2016 2SS. If the oil covers all of the hatched portions on the stick, it’s good to go. I change my own oil anyway so I know how much oil I put in the engine when it’s changed.

Temperature plays a big part in oil level. Whether it’s a diff, hydraulic tank, transmission, engine, final drive, the oil will shrink when it’s cold and grow when it gets hot. This is a main reason why they say to check certain oils idling at operating temperatures. Some oils expand more than others.

Yep and i am getting the most accurate consistant results after engine is warmed up then sits for about an hour.


If the temp outside is warm, checking it when fully cold should be ok too.


But ya my mystery is solved, i was pretty much overfilling my oil thinking i was burning it. I now just keep it mid level on the cross hatch.

Same that has happened to me several times I could send pictures where it was half way up the dip stick. Made no sense. Next day normal. If I didn't take the pics I wouldn't believe it myself. The most crazy thing ever.

I think the manual says wait 10min after shutting down to check. I went through the same thing the other day. I thought I was going crazy.