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Join Date: Feb 2009
Location: South Africa
County: Northern Cape
Running low on oil should theoretically not affect the bearings in any way, since the oil pump intake is situated at the sump bottom (except with a very low oil level or near-empty sump, in which case you would have seen the oil pressure warning light coming on).
Running low on oil may increase the wear rate of the sleeves and piston rings, since the lubrication of these are dependent on the splash feed of the oil by the turning crankshaft. A very low oil level may result in some areas not getting splashed with oil as frequently as with a normal oil level.
I therefore recommend that you just keep an eye on the oil level in future. If frequent topping up is required, it is an indication of worn sleeves and rings.
If the rings and sleeves has worn to a state where you start considering an engine rebuild, you may do an economic break-even analyses. You will find that you can do a lot of topping up with oil before a rebuild is economically feasible. Normally a rebuild is only required when a loss in compression results in a loss in performance that is no longer acceptable to you.
For a long engine life, it is important to change the oil (and filter) frequently (not exceeding 10 000 km) since:
- there is an exponential build-up of impurities in the oil, contributing to increased wear. The main 3 impurities are:
1) silica, from fine dust passing through the air-filter.
2) iron, from wear of engine components.
3) carbon residues from burning fuel.
- the molecular hydro-carbon chains of the oil gets broken with use. This results in the oil getting thinner with prolonged use, resulting in a lower oil pressure, due to oil escaping more easily through some of the pumped oil-ways, and other oil-ways suffering from oil starvation.