I bought a 335I leased by a guy who worked at the stealership with about 35K miles on the clock. After assuming ownership, I started using total engine oils (quartz 0W30, 10W50, Ineo MC3 5W30) with an oil change at 8,500 miles + motor flush. My car didn't have an oil cooler and ran hot during the summer (240-266F). I drove mostly highway miles at about 400+ per week. I took off my oil filter housing at 68K miles, and sold it to a guy who sold me his which had the thermostat and oil cooler.
From 35-60K miles, my oil filter housing had quite a bit of sludge and soot on the outside, and layers of soot on the inside piping. His in contrast was clean on the outside, and on the inside piping. I asked what oil he ran, and to my surprise, he had been running castrol syntec 5w30 for 38K miles, with oil changes every 5,000 miles. He also didn't clean his oil filter housing before selling it to me.
I now am seriously re-thinking the conventional thinking on motor oils that I picked up on BITOG, and the BMW forums. People are obsessed with oil analysis, and oil approvals. I thought that I would be ok with 8.5K mile oil intervals in this engine, with the motor flush as added protection, but now I think I was wrong. during the summer months after my long daily commutes to work, I would pop the hood and see the oil (sludge) boiling and bubbling out of the oil filter housing cover. This would only start happening after the oil was run for more than 7.5K miles. This is how the sludge and soot built up on the outside and inside. So it would seem that unapproved semi-synthetic generic castrol syntec, changed at 5K miles is superior to these heavily approved, synthetic based oils run for more than 7.5K miles!
From 35-60K miles, my oil filter housing had quite a bit of sludge and soot on the outside, and layers of soot on the inside piping. His in contrast was clean on the outside, and on the inside piping. I asked what oil he ran, and to my surprise, he had been running castrol syntec 5w30 for 38K miles, with oil changes every 5,000 miles. He also didn't clean his oil filter housing before selling it to me.
I now am seriously re-thinking the conventional thinking on motor oils that I picked up on BITOG, and the BMW forums. People are obsessed with oil analysis, and oil approvals. I thought that I would be ok with 8.5K mile oil intervals in this engine, with the motor flush as added protection, but now I think I was wrong. during the summer months after my long daily commutes to work, I would pop the hood and see the oil (sludge) boiling and bubbling out of the oil filter housing cover. This would only start happening after the oil was run for more than 7.5K miles. This is how the sludge and soot built up on the outside and inside. So it would seem that unapproved semi-synthetic generic castrol syntec, changed at 5K miles is superior to these heavily approved, synthetic based oils run for more than 7.5K miles!
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