One of my cars a 1998 Pontiac Sunfire GT. It was purchased used in Jan of 2002 and fed Quaker State 5w30 (10w30 in the summer) and a Fram filter every 5000kms. The oil is always drained hot and the oil level is kept to the full line. In Aug of 2004 the Sunfire was close to the 100,000km mark. It this point I decided to switch to Amsoil. I used Amsoil flush, and new filter and ran it for 20 min (approx) and the Quaker State came out Amber in colour. I installed Amsoil 10w30 (ATM) and a SDF32 filter, also did a tune up. The oil slowly became dark. At 105,000kms I installed a new SDF filter and topped it off. The oil was still fairly dark. At around 112,000kms the oil became black. I emailed Amsoil and asked why is my oil turning black. They said colour does not indicate condition.
At 115,000kms the car became consuming a high rate of oil. It would not hold oil. The oil looked very thick and very black. I put some on paper towel, black as used diesel oil. Remember Amsoil said black is normal. At 117,000kms I noticed specks of rust forming on the dipstick. I panicked and drained it. At this point I installed 4 quarts of Amsoil 0w30 and SDF filter. No flush was done. At 123,000km the oil was dark (not black) and half quart low. So I drained it, but I did not add any. Stuff costs too much. This time I filled it with Amsoil 5w30 (ASL) and an AC Delco filter. At 133,000kms, 143,000kms, 153,000kms the oil was changed with Amsoil 5w30 again with AC Delco oil filter every time. The car now has 159,000kms. The car used ¼ of a quart every 5000kms with Quaker State. Oil consumption is essentially the same with Amsoil. Except that one time, the last 2000kms of my first interval with Amsoil. The engine has felt “loose” for the last 40,000kms, but remains to runs fairly well HP wise.
