When inspecting the engine oil level dipstick of a 2007-2009 Mazda CX-9 or 2009 Mazda6 vehicle equipped with a 3.5 or 3.7L engine, it’s important to understand that the engine design causes oil to drain back to the oil pan sump at a slower rate than other Mazda engines when the engine is shut off.
During engine oil service or checking, after filling the engine with the correct amount of oil and running the engine to circulate the oil, wait approximately five minutes before checking oil level on the dipstick. If you don’t wait long enough, you will assume that additional oil is required, which could result in overfill. This can cause engine oil foaming as the crankshaft counterweights whip through the oil, with subsequent bearing damage.
Add oil and be patient before reading the stick.