Old gaskets on my Lexus is300 caused oil to drip onto the exhaust manifolds and spark plug well. VERY BAD! With these seals, NO OIL will escape! TIP>>> If you smell burning oil in your car, this could very well be the reason described above.>> While the job may seem very difficult, it is not that difficult. It is highly recommended that you replace the spark plugs (since you are already there). DENSO SK16R-P11 iridium spark plugs only. Since already in the engine I replaced the spark plugs, spark plug wires, coil packs, injectors, gaskets (from the exhaust and intake sides), cleaned the candle channel and cleaned the throttle body.