My car's engine has a metric mechanic stock rebuilt head (change your timing belts kids!) with about 35,000 miles on it-while the short block has 177,000 on it. Seems to consume a bit of oil and I suspect some oil getting into the coolant. I'm accepting that a rebuild is on the horizon would really appreciate some advice. Local machine shop? "BMW specific machine shop" ? Also have an eta block on hand (believed the myth) is that worth investigating? Metric mechanic lists a conversion.. Well, anyone that's been through the "big engine work" please reply. I'd like to keep the head as-is and just rebuild the bottom end as cost effectively as possible-is there a performance gain to be had for around the same cost and hassle as a stock rebuild? When do I know it's time to get moving on it? Thanks all.