Could transmission fluid be leaking into the crankcase?

Dear Car Talk | Mar 01, 1993
Dear Tom and Ray:
Richard
TOM: Gee, Richard, I don't know. I can't think of any way transmission fluid could be getting into the crankcase. I mean, it's as unlikely as air from your front tires sneaking into the spare in your trunk.
RAY: It is possible to lose transmission fluid without seeing it on the ground. If the transmission's vacuum modulator were faulty, it could be sucking out transmission fluid and dumping it into the carburetor. If that were happening, the fluid would be combusted along with the fuel, and would come out the tailpipe as smoke.
TOM: But the increase in oil? I can think of a couple of explanations for small variations in oil level...like plugged drain holes in the upper end of the engine, or gasoline seeping down past the rings. But neither of those would explain an extra four or five quarts.
RAY: So my theory is that someone is making a mistake. I think S.O.'s gas station attendant (a seventeen year old kid named Butch) is "checking the oil" every time she stops to get gas. But instead of pulling out the engine oil dipstick, he's accidentally checking the transmission dip stick. So every time he sees you're down a quart of TRANSMISSION fluid, he dutifully adds a quart of ENGINE OIL to the CRANKCASE.
RAY: Tell S.O. not to let anybody open the hood under any circumstances for the next month, and I'll bet this problem goes away.
TOM: And if not, why not make the most of it, Richard? Call OPEC and find out how much they'll give you per barrel.
Richard
TOM: Gee, Richard, I don't know. I can't think of any way transmission fluid could be getting into the crankcase. I mean, it's as unlikely as air from your front tires sneaking into the spare in your trunk.
RAY: It is possible to lose transmission fluid without seeing it on the ground. If the transmission's vacuum modulator were faulty, it could be sucking out transmission fluid and dumping it into the carburetor. If that were happening, the fluid would be combusted along with the fuel, and would come out the tailpipe as smoke.
TOM: But the increase in oil? I can think of a couple of explanations for small variations in oil level...like plugged drain holes in the upper end of the engine, or gasoline seeping down past the rings. But neither of those would explain an extra four or five quarts.
RAY: So my theory is that someone is making a mistake. I think S.O.'s gas station attendant (a seventeen year old kid named Butch) is "checking the oil" every time she stops to get gas. But instead of pulling out the engine oil dipstick, he's accidentally checking the transmission dip stick. So every time he sees you're down a quart of TRANSMISSION fluid, he dutifully adds a quart of ENGINE OIL to the CRANKCASE.
RAY: Tell S.O. not to let anybody open the hood under any circumstances for the next month, and I'll bet this problem goes away.
TOM: And if not, why not make the most of it, Richard? Call OPEC and find out how much they'll give you per barrel.
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