When I go to check my ATF level while the engine is running at operating temp I see several little bubbles in the fluid. When I first saw this I figured my level might be a little high and I'm getting some foaming. It seems to be very difficult to get a consistent reading with these trannies. So I drained about half a cup of fluid and now I'm a good 1/4 of an inch below the minn. line and there are still some bubbles. The fluid is bright red and super clean. Since the car is new to me, I don't know the history of the transmission's service intervals, but am wondering if ATF can be clean but maybe worn out. Any thoughts? Thanks

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'81 300SD