TSB identified a broken titanium stud as part of the gearbox oil filter assembly. Other parts are re-engineered to provide ease in changing the oil filter. It had a downward facing oil filter housing. The oil filter was mounted remotely. The overpressure relief valve is frequently incorporated into the oil filter. Canister style oil filter at bottom front of engine. The Purolator oil filter is still in production today. The four-cylinder engine received an in-pan oil filter element and balance shaft. An unusual feature on early models was the absence of a spin-on paper oil filter. One suggested cause for the failures was the oddly shaped and located oil filter. A full-flow oil filter became standard across the range. It featured a seven-bearing crankshaft, full flow oil filter and hydraulic valve lifters. This was the last year for the spin-on oil filter on the four-cylinder. The first all-plastic oil filter in the world followed in 2003. Lighter, smaller oil filter and front brake calipers were lifted from the super-sport CBR900RR.