A few weeks ago, I suspected I might have overfilled my beloved 1997 Mini with too much engine oil. I didn't know where to go for advice, so I went to the place where we always go these days: google.
And here's the first search result I found, courtesy of Young's Garage of Tealby, which if you didn't know (as I didn't), is a rather lovely village in the Lincolnshire Wolds:
What happens when an engine is overfilled with oil?
So you topped up the engine when it was warm after getting a faulty dipstick reading, or you put too much oil in when you changed it yourself. What's the worst that could happen? Well the problem with this is that the next time the engine is run, the windage in the crankcase and other pressures generated by the oil pump, etc. place a great strain on the seal on the rear main bearing.
Eventually, often much sooner than the ordinary man in the street might expect, the rear main bearing seal ruptures, and the engine becomes a 'leaker'. If you've got a manual gearbox, this means one thing: this oil goes right onto the flywheel and the face of the clutch disc. A lubricated clutch is A Bad Thing. If this still goes unnoticed, the front seal is the next to go, and the engine then becomes a 'gusher' (or to be more colourful, it starts pissing oil all over the place). As well as smothering the clutch with oil from the rear, the oil now coming from the front leak will be neatly distributed about the engine bay as it hits the front pulley - often propelling it out as far as the brake discs. At the same time as this Hollywood disaster movie is unfolding outside the engine, things aren't working out any better on the inside. As you can see from the diagram, the correct oil level is really close to the rotating crank. Overfilling will mean the crank dips into the oil and churns it into a froth. Froth is good on certain types of coffee but not good in an engine. The mixture of aerated oil will be forced into the bearings and in case you didn't know, air is not a lubricant. Typically this means that bearing damage will follow quite rapidly, especially if you are driving on a motorway. You'll know bearing damage when you get it. The engine smells like a garage mechanic cooking over an open flame and the noise coming from the engine is the sort of thing you'd normally hear in vaudeville plays when a piano is pushed down a flight of stairs. As if that all wasn't bad enough, the excess oil gets thrown up into the piston bores where the piston rings have a hard time coping with the excess oil and pressure. It gets into the combustion chamber and some of it will get out into the exhaust system unburned resulting in a nice patina of oil all over the platinum surfaces of your catalytic converter. This renders it utterly useless for good. Well, you did ask.
So there it is.
Copy that actually tells you things you don't know.
No dumbing down, on the assumption that the reader only wants inanity.
No contrived 'tone of voice', but just informed writing, with the author's wit and personality mixed in for good measure.
It reminds me of one of the greatest ads ever written, Charles Saatchi's 1970 poster for The Health Education Council (see below). There, the copy could have come straight from a textbook on food hygiene, with a tweak here and there.
Equally, the garage copy could have (but I'm sure didn't) come straight from a Haynes manual, but with the extra wit added in to make the subject of engines, unlike the subject of flies landing on food, more palatable.
So thanks, Young's Garage. As it happened, I hadn't overfilled my engine. But if I had, I'd have had the car put on a trailor, and taken straight to Tealby. Testimony that good copy brings in the customers.