1. When is the right time to check the oil in my 91 7.3 - cold or at operating temp? Sorry, I don't have the owners manual.

2. I opened the radiator cap this morning and it was still pressurized. The truck had not been run in 24+ hours. What could cause that? could it be a blocked heater core because I think mine is blocked.

Thanks in advance.

 

Warm oil is the correct time to check it, give it a couple minutes drain time after you shut it off.

Was there pressure or a vacuum in the cooling system when you checked the radiator?

I have noticed a vacuum when I have checked mine several times.

 

Dave,
Thanks! It was pressure when i took the radiator cap off. Kind of scared me...

 

Pressure could be caused from the fact that the last it was opened it could have been cold outside, and so now this time when you opened it, it is now warmer outside, thus pressure is built because I bet your overflow outlet is clogged.

 

According to the sun viser on min run the engine to operatting temp then shut it off and wait 25 minute to alow oil to drain then check it. What a pain.

 

I woder how they came up with 25 mins. instead of 1/2 hour?

 

I wounder how may people actauly checked the oil like that in the u-hauls with 7.3s and 6.9s that say to check the oil every time you stop for gass.

 

I wonder how many people ever check the oil in a U-Haul?

 

i dont know nothing about u-haul, but i check my oil almost everytime before i get into it, whats 2 minutes vs. 4500 dollar rebuild, just a piece of mind

 

i should check mine everyday but i find bout once a week will suffice as long as is not leaking. i only have to add bout half a gallon oh every two to three weeks or so, depends how hard i run it.

 

I was called out one time on a u-hual that was smoking bad and no power.
It turned out the guy had been adding oil every stop trying to keep it full like they told him and he had it full literaly.

 

if i run mine real hard and be mean to it i can go threw oil quick