The Math isn't lining up (1 Viewer)

[offroadvegan]

So when my oil light comes on, I am just about exactly 1 Qt. low. Oil light has not been on in a long time. Dipstick looks good (although sometimes it reads waaay over F).

Just completed an oil change, and decided to measure the amount that came out of the pan.

According to this pic, I only had about 6 quarts in the vehicle. Some is still in the filter, but I did let it drain as much as possible.

So that is 1.8Q below full. But dipstick was fine prior to the change, and the oil light was NOT on.

What gives?

PS. Using OEM filter and full synthetic oil.

 

[mct75]

When was the last time your 1FZ had a prostate exam?

 

[offroadvegan]

When was the last time your 1FZ had a prostate exam?

Last January. Full colonoscopy and prostate check.

 

[REKCUT]

Don't believe that draining the oil pan will get every all the oil out of the truck. From what i have read a "Dry" engine requires 1 to 1.5 more quarts then on an oil change

 

[REKCUT]

That said, If the truck showed full, you should be putting back in the exact same amount you drained out. Did you put in 6 quarts or did you put back in closer to 8

 

[LINUS]

Bigger question:

Why are you using your “low level” idiot sensor for anything?

Dip your stick more often & quit being lazy.

If you insist on using a 20yr old sensor for knowing your engine “blood level”, that’s on you.

You don’t even need to do the whole hood “prop rod” thing, so check your oil more often & keep it in the top 1/2 of the hatches on the stick. Problem solved.

 

[Marine7]

Agree with Linus..... DONT make this harder than it is. Check your dipstick every time you fuel up.... in an 80 series that not more than a couple of days!

 

[b4wheeler]

My low oil light does not come on until "3 qts" low.

Guess how I found that out........

Now I check every other fill-up. So twice a week........J/K

 

[offroadvegan]

So I guess more backstory is needed.

I don't rely on the light. I am not lazy. On a recent round trip drive from OR to LA, it did come on, and I immediately filled it up. It was one quart low.

@REKCUT I did about 7.5 but kept checking the stick. Started it, let it all cycle, and am at the F.

 

[LINUS]

OK, well - if you’re not lazy and your sig applies, your rebuilt motor is drinking oil like one with 200K valve stem seals & tired crank seals & pan & cover gaskets.

How you can swing the oil level so much is odd IMO.

Mine has mid 140K on it & while I don’t lose any oil between 3K changes, I still check it plenty often. I did stem seals with my HG some ~20K ago (& the valve cover gasket/plug rings), but all other seals/gaskets are original & I drip a trace amount.

Why are you using high milage oil on a rebuilt motor?
You shouldn’t be using more than 1/4-1/2qt between changes, assuming 3-3500mi between changes.

Honestly, mine is an exact science of oil out = exact going in. Like I’d expect.
I’ve never even seen that idiot light in any of my 80’s, so I’d crap sideways if I did.


——Time to start parking over cardboard, I’m thinking you got a problem seal.

 

[flintknapper]

So I guess more backstory is needed.

I don't rely on the light. I am not lazy. On a recent round trip drive from OR to LA, it did come on, and I immediately filled it up. It was one quart low.

@REKCUT I did about 7.5 but kept checking the stick. Started it, let it all cycle, and am at the F.

I think the answer to your original question is that you were a bit low and you might have been expecting the factory specified capacity (dry engine) to drain out. This simply wont happen. Clearly you wont get all the oil out of the oil filter. The oil pump holds a certain amount as does the oil cooler. Each and every oil galley will have some residual film if not fluid.

Drain the system to your satisfaction and then add back oil until it shows full on the dip stick. I generally put in 8 qts. but I run a large filter (Motorcraft FL-1) and I have some leaks. So your 7.5 sounds about right to me.

You're fine.

 

[offroadvegan]

OK, well - if you’re not lazy and your sig applies, your rebuilt motor is drinking oil like one with 200K valve stem seals & tired crank seals & pan & cover gaskets.

How you can swing the oil level so much is odd IMO.

Mine has mid 140K on it & while I don’t lose any oil between 3K changes, I still check it plenty often. I did stem seals with my HG some ~20K ago (& the valve cover gasket/plug rings), but all other seals/gaskets are original & I drip a trace amount.

Why are you using high milage oil on a rebuilt motor?
You shouldn’t be using more than 1/4-1/2qt between changes, assuming 3-3500mi between changes.

Honestly, mine is an exact science of oil out = exact going in. Like I’d expect.
I’ve never even seen that idiot light in any of my 80’s, so I’d crap sideways if I did.


——Time to start parking over cardboard, I’m thinking you got a problem seal.

Well, just to add more mystery. I don't have any leaks. And exhaust is clean, no burning oil. I was wondering if maybe it just doesn't like synthetic?

I am hoping @flintknapper is right.

 

[Fj81]

My low level light has a mind of its own. I may just take the bulb out right now when I put the LED cluster lights in, since I always check the level manually anyhow.

 

[REKCUT]

When the simplest answer is usually the correct answer, if it was full when you drained it and you only got 6 1/2 out but you got almost 8 back in, then i would say that you possibly misread the initial reading and it was a little over a quart low to start. make notes and do it again next time.
Good luck. Things like this also bother me

 

[offroadvegan]

When the simplest answer is usually the correct answer, if it was full when you drained it and you only got 6 1/2 out but you got almost 8 back in, then i would say that you possibly misread the initial reading and it was a little over a quart low to start. make notes and do it again next time.
Good luck. Things like this also bother me

I hope you are correct, and most likely are.

What kills me with this 80, is the damn dipstick. I can get 3 different readings with 3 different pulls.

 

[flintknapper]

I hope you are correct, and most likely are.

What kills me with this 80, is the damn dipstick. I can get 3 different readings with 3 different pulls.

Oil Gremlins. Hate them.

Fill it, drive it, let it sit, check it after a couple of hours. Add if needed...but honestly if you are anywhere in the window of being a quart over to 2 low you are still fine. The 80 series doesn't care. Don't sweat it.

 

[REKCUT]

I hope you are correct, and most likely are.

What kills me with this 80, is the damn dipstick. I can get 3 different readings with 3 different pulls.

Cold start, run for 5 min. check.

Always shows less if i check it after it sits all night.

 

[flintknapper]

Cold start, run for 5 min. check.

Always shows less if i check it after it sits all night.

Makes sense. When the oil is hot (operating temp) there will be a certain amount of thermal expansion.

 

[LINUS]

Makes sense. When the oil is hot (operating temp) there will be a certain amount of thermal expansion.

I’m a little dubious of this.

We filled pumpcases with gallons of oil & would hit the mark dead on, when run the oil never grew over the mark.

Regardless, I say just develop your own repeatable way to dip the oil @offroadvegan

I personally give it ~20mins after hitting self cleaning to let the oil drop down out of the case, so I don’t get a false low like if you pop the hood at the gas pumps.

 

[clx16]

For mine halfway in the hashes I can get the idiot light to come on for a second or two. add one quart and it gets back to the full line. I think the sensor is very old. This has happened several times so I am happy about it. I don't mind getting a 1 quart warning. I DD mine and that means 1 quart a month.
I don't really worry about it, Logically I would try to find a more accurate sensor, but then things would change and i don't like change.