BLUF: You need to do both cold and hot oil level checks to avoid M113A3-series vehicle engine damage.
Is it best to check the engine oil levels in your M113A3-series armored personnel carrier when the engine is cold or hot? The correct answer is both
The PMCS charts in TM 9-2350-277-10 (Aug 22) say to do an AFTER OPERATION hot check, while the lube order (LO) says to do a BEFORE OPERATION cold check. Both the TM and the LO are correct. Just keep in mind that you’ll get different readings based on whether you do a hot or cold check.
A BEFORE OPERATION cold check, while not completely accurate, keeps you from driving the carrier if it’s dangerously low on oil, which leads to damage.
The oil level should be at or just above the dipstick’s F (full) mark for a cold check. If the level is below the L (low) mark, call your mechanic to check for leaks. And if it’s far above the F mark, she or he may need to drain some oil.
An AFTER OPERATION hot check is the most accurate and the one the dipstick was designed for. To check the engine oil, shut down the engine after it reaches operating temperature. Wait 3-5 minutes and then check the oil level. You should get readings between the L and F marks.
If either the hot or cold check shows an engine oil level below the L or above the F, let your mechanic know right away.