More on oil
Posted: Tue Aug 18, 2009 8:44 am
At the risk of starting a religious discussion...
I've always (for the past several decades) used Castrol GTX in all my engines, and I've never had any oil-related problems. But I was a bit worried about BMW's decree that SJ-or-later oils did not provide adequate anti-wear protection. OTOH, GTX is rated SH, SJ, SL, and SM, so I figured if it meets SH, it should be OK for BMW. I asked Castrol, and they (lamely) replied to do whatever the manufacturer recommends. I couldn't get a straight answer from my dealer. So I, somewhat nervously, used the GTX (in 20W-50).
I just came back from a trip of about 7000 miles, including a lot of high speed work at ambient temperatures up around 100 degrees F. And my total time on the oil was around 7500 miles, "stretching" BMW's recommendations by more than a bit. So I sent an oil sample to Blackstone Labs.
Their report was very encouraging: Wear was lower than average on all measures. Viscosity was still well within the expected range. And TBN (Total Base Number) was 4.6, where 1.0 indicates the additives are approaching exhaustion. Blackstone commented that I could "easily run the next oil longer, try 8500 miles."
I probably won't do that, I'll try to stick with BMW's 6000-mile number. But I now feel pretty good about continuing with the GTX. I don't see any reason to change.
FWIW,
I've always (for the past several decades) used Castrol GTX in all my engines, and I've never had any oil-related problems. But I was a bit worried about BMW's decree that SJ-or-later oils did not provide adequate anti-wear protection. OTOH, GTX is rated SH, SJ, SL, and SM, so I figured if it meets SH, it should be OK for BMW. I asked Castrol, and they (lamely) replied to do whatever the manufacturer recommends. I couldn't get a straight answer from my dealer. So I, somewhat nervously, used the GTX (in 20W-50).
I just came back from a trip of about 7000 miles, including a lot of high speed work at ambient temperatures up around 100 degrees F. And my total time on the oil was around 7500 miles, "stretching" BMW's recommendations by more than a bit. So I sent an oil sample to Blackstone Labs.
Their report was very encouraging: Wear was lower than average on all measures. Viscosity was still well within the expected range. And TBN (Total Base Number) was 4.6, where 1.0 indicates the additives are approaching exhaustion. Blackstone commented that I could "easily run the next oil longer, try 8500 miles."
I probably won't do that, I'll try to stick with BMW's 6000-mile number. But I now feel pretty good about continuing with the GTX. I don't see any reason to change.
FWIW,
