The excessive oil consumption you are experiencing is probably due to the oil being burnt off. I agree that the internal components are probably out of manufacturing tolerances. Possible worn bearings and/or piston rings. The burning engine oil has left heavy residue, varnish or shellac on the cylinder walls and MAY have caused the ring to stick leading to the breaking of a connecting rod. It is possible, but I am guessing, that a faulty oil pump, in the first instance, lead to oil not being circulated in the fine galleries which subsequently lead to the premature wearing down of the said components. Or it may be that residue or deposits in the fine galleries prevented proper circulation of oil. If too thick an oil was used all along, like say a 20w50, then this may have contributed to the improper circulation of oil, subsequent formation of residues and deposits, blockage of fine channels and galleries. In California some new cars specify 20 weight oil to keep within emmisions laws! Using a 40 weight oil or a 50 weight oil would be disasterous in such an engine.
They may have put a thinner grade of oil along with the new pump but it may have been too late, such that the new thinner oil burnt off because the rings are so worn.
I wouldn't say that it is the shop's fault for the blown rod but you could seek to go halves with the shop for a rebuild?
If you say you saw the oil pressure drop to zero while driving, you will be asked why you did not stop to check the oil level.
Hope this helps.
Wednesday, November 18th, 2009 AT 9:52 PM