Some time back a friend was boasting that his oldie never used oil. No amount of persuasion could convince him that that particular engine had to use oil otherwise it would die a premature death. Looking at the dip stick he was right it was full to the top mark and even beyond but the smell of the oil confirmed the problem was that the sump wasn’t full of oil but a high percentage of petrol was added.
I was recently reminded of this when looking at a weekly episode on cars by John Cadogan, the Australian chap who has a weekly programme on some technical issue or the other. By the way, if you want a bit of free entertainment look him up on Google. This particular episode was about the necessity of changing oils in modern cars at the intervals prescribed by the manufacturer and the consequences if you don’t.
Although he was referring to modern engines I think his advice is even more applicable to our oldies. Older cars fitted with carburettors tend to over fuel at the best of times especially when cold. Years back I recall that it was imperative to change on the dot every 1000 miles.
Cadogan rightly points out that we so often use our cars for short trips resulting in the engines taking too long to warm up to the correct operating temperature with the result that the unburned fuel ends up flooding down the pistons and mixing with the oil seriously reducing the oils viscosity. We are also reminded that petrol is not a very good lubricant.
The answer – play safe and change the oil at regular intervals. Yes, it’s getting expensive but still a lot cheaper than a premature engine rebuild.