Sunday, 18 September 2011

A short and informative post about oil and gunk

    A few weeks ago I was in despair. Black grot everywhere, a very sickly sounding Wreck indeed, and an alarming consumption of oil had left me convinced that the older of my two cars had a broken piston ring, something that is rather annoying to fix.
    So I borrowed C's compression tester, a pressure gauge on a bit of pipe you screw into the hole where the spark plug goes, and measured the compression on all four cylinders. Perfect, all nearly the same, and all exactly where I expected them to be. This is an old engine, and it was designed with a low compression to run on the nastier grade of 1950s British petrol.
    So the car hadn't destroyed a piston ring. Great. So what's up?
    Back in the summer I overheated the car as its aged 1950s thermostat failed. Fortunately it's a tough engine so it can take it, but unfortunately it boiled its oil and a lot of it escaped in an impressive cloud of smoke. I had to buy a can of oil from a garage, and they didn't have the old-style 20w50 grade that used to be the mainstay lubricant for cars like the Wreck. I bought modern 10w40, a much thinner and more high-performance oil that wouldn't do the Wreck's engine any significant damage but definitely isn't the one recommended for it.
    I think I've found out why 10w40 is not recommended for Wrecks. The thinner oil seeps past the aged rubber oil seals with ridiculous ease, which meant the cylinders were filling with oil from above rather than below as it flowed past the valve stem seals.
    An engine flush that brought out an impressive amount of thick black gunk with the used oil, followed by new 20w50, a new filter and a can of oil seal rejuvenation additive, and I once again have a car that shows some semblance of reliability.
    Why on earth do I run a car that does things like that to me? If you have to ask, you just don't understand. :)


  1. Dear Jenny,

    Glad to hear your ride is running well again. Just got in from the big annual British car show at Bronte Park in Burlington. I will post some pictures later.



  2. I remember the advent of shell Gemini 15W50 at £9.99 a gallon, an oil that did not get thin when hot that stayed in the sump where it was supposed to be and kept oil consumption to a respectable level.

    Alas it looks like you are stuck with the traditional 20/50 now that the high performance oils all appear to be only available in much thinner grades.

  3. I don't have to ask...! But I'm certainly impressed that you can get an additive to rejuvenate your oil seals. Bet it's not L'Oreal, too.

  4. I do not understand.....LOL
    Surely there must be more than one grade of oil to be had?

    Shirley Anne xxx

  5. Morning all, circumstances have conspired against my having a chance to address myself to this blog of late.

    I am sure I could lay my hands on a more high-performance oil in the grade I need. Racers use them, for one. But this is an unstressed 50 year old engine not a high-performance machine.

    The additive is called "Wynn's stop leaks". I have a complete faith in all the little bottles of magic stuff you can buy from Halfords. If I used them all at once I calculate that the combined claimed power boost from all of them should be enough to give me Formula One levels of power at the same time as infinitely extended engine life. Like I said, complete faith. :)

  6. Thank you, Jenny, for this most valuable information, should I ever acquire a wreck.