Classic cars forum & vehicle restoration.

[Uncle Joe]

[split from my A55 thread.. RJ]

Really, this answer warrants its own topic, so if you wish to move it, by all means do so. In no way though am I saying anything negative about your choice of oil. I'm passing on some observations that I have made on another engine.

The example engine in question is the 3.5hp B&S that is fitted to my lawn mower. Being a side valve, I think that it can be considered ''typical'' of a classic era engine. I dont know how many hours this engine runs per year, but to give an idea I use 1 tank every clip, which is every third day, weather permitting. note also that I use R40 as a UCL. B&S recommend SAE30 for this engine. Run it on that, and as long as it is changed once per season, it never seems to use oil. Change to 20/50, and this particular engine needs topping up after every mowing session. I would guess around 250ml.

For quite a while now, I have been using a particular brand 10W/40 in all of my vehicles that will allow this. As I usually have some over, this gets used up in my garden machinery. The curious thing is, none of the B&S engines use (burn) this oil, though the only Tecumseh that I have, a 5hp, does...

[peter scott]

[Uncle Joe]

Basically, its build up of deposits in oilways. Remember that we have old engines that can have large amounts of these. High detergent oil tends to loosen them, and thereafter the problems. This information could possiblt be found on some of the oil companies website, I would think.

Of course, if an engine has been cleaned properly during a rebuild, these problems wont occur, but I have seen several so called pro engine builders/reconditioners that just simply dont do this correctly. And I would be willing to place a bet that even some of us that have assembled our own engines havent bothered to check oilways, etc. for cleanliness.

Why do I get the feeling that I have just opened a can of worms...

[peter scott]

[Uncle Joe]

The trouble is Peter, I see far to many people nowadays that are just to lazy to do a job properly...

This is unique, two engineers agreeing!