LB7 oil magic trick

[Gizmo]

LB7's magic trick. Hide the oil.
My LB7 oil level has always been difficult to get a repeatable reading but this is a doozy. It will go from normal (full on dipstick) instantly to “OIL LOW” on startup. Oil pressure holds but the oil has actually disappeared!! On shut down just the very tip of the dipstick shows oil. The cure is to drive it a few miles with the “OIL LOW” message glaring at you, shut it down and check oil again. ZA ZHAM, my LB7 has given all the oil back! It is now back to the top of the dip stick!

It has done this trick 2 or 3 times a year since almost new and in no pattern I can see (hot, cold, etc, etc). It does no damage but I just hate when that low oil light comes on right at startup.

Any ideas?

Gizmo

2002, LB7 with 147K miles. Most of those miles were pulling a 33 foot 5th.

[More Power]

I've only seen the low oil warning once in nearly 13 years - due to neglecting the oil level. It was low, but the engine never lost oil pressure.

For you, there are a couple possibilities.

1- You live in a cold area, and the oil is pulled out of the pan faster than it can drain back, tripping the oil level sensor (though I've not heard of this happening before).

2- Your oil pan's level sensor is a bit finicky.

When the engine is cold, we're cautioned to not check the oil level till several minutes have passed with the engine off. A cold engine that was just shut off will produce an artificially low oil level because the cold oil won't have had a chance to drain back to the pan.

Welcome to the board!

Jim

[Gizmo]

Jim,

I don’t know how oil flows in the block but your idea about oil not returning to the sump fast enough when cold makes some sense.

1) From full oil indication to the just the bottom of the dipstick is how much oil? A quart?
2) Where could it be hiding that much oil when cold? In the valve covers?

I’ll change oil before winter storage on a warm day next week (I don’t drive my truck in winter salt). Rotella T6 synthetic 5W-40

Thanks for your thoughts;

Gizmo

[More Power]

1) From full oil indication to the just the bottom of the dipstick is how much oil? A quart?
2) Where could it be hiding that much oil when cold? In the valve covers?


Yes, the markings on the stick are calibrated to indicate a quart and fractions thereof.

Cold oil clings to everything exposed to the oil. This delay in drainback could equal up to a quart, I suppose.

I check oil one of two ways... 1- Just before a cold start. 2- After a hot/warm engine has been shut off for several minutes. And, try to park the truck on the same spot each time, to reduce the effects of uneven ground.

It's best to be consistent in how you check the oil - at least till you become more familiar with how the oil level can change depending on how you check it. For a time, always check the oil level either before a cold start or after a hot/warm engine has been switched off for say 10 minutes. Just be consistent. Jim