From various documentation it's understood that many of these older designed engines didn't actually have a specific type of oil that could be mixed with fuel to provide adequate lubrication of the moving parts. It's generally understood the train of thought at that time was to use a 30 weight car engine oil. CAR ENGINE OIL i hear you say? Apparently so... but remember that's all that was available in those days, and so a lot of that "old thinking" has stuck and keeps on being repeated again and again. That's fine.
BUT these days is it still the right thing to do for our older and perhaps quite tired and worn engines today? There are 2 schools of thought here.
1 If it was good enough back then, surely it will still be good enough today. Maybe... but things have progressed hugely from the 1930's especially when it comes to the humble oil we use in pretty much any engine today.
2 Gaining experience from the old ways, and constantly looking forward to the future with science and a little bit of chemistry on its side, the modern variants of oil these days are a very far cry from the old days.
So, what's the difference between a mineral oil and modern semi synthetic and fully synthetic oil. What are the benefits to using this stuff. What can it do for my engine. Will it cause damage to my older engine?
I'm certainly not an expert here, but i have had a fair bit of first hand experience from looking at engine failures in a LOT of different engine types over the years. To help explain things a bit further i'm going to refer you to these guys for a minute. Bear with me here as most of the information he talks about is more relative to 4stroke engines, but there are a few bits that directly relate to what is relevant here.
http://www.carbibles.com/engineoil_bible_pg2.html
If you're still with me after that, well done so far.
Now then, the issue of using car engine oil in our pre-war seagulls.
Again, the camp is divided here, and another link although they talk about lawn mower engines (not too dissimilar to a seagull in many respects)
https://www.smokstak.com/forum/showthread.php?t=23278
Interesting point there in the last post.
The more oil you use in the fuel mix, you actually lean out the fuel getting through to where it's needed.
More oil in the mix isn't always the best course of action here, perhaps more relevant to our older seagull engines.
10:1 or maybe even 8:1 back in the good old days was considered to be acceptable, but remember there wasn't any specific grade of oil for 2strokes back then. Sounds a bit odd, but it's true.
Nowadays there's a whole plethora to choose from. Some of it quite confusing too if you read through the last link, especially to some of you older gents out there that refuse to step into the 21st century. (i'm trying to be kind here)
That's fine too, i'm not pushing anyone here. Just trying to re-educate is all.
These guys are getting a bit closer to the REAL QUESTION here. Is it safe for me to use a modern oil in my old seagull?
http://forums.iboats.com/forum/engine-r ... er-engines
Less is more... (oil that is)
Might help to understand why there's different grades of oil for different purposes, AND how different oil manufacturers achieve their different grades. Most of this is relevant to 4strokes though, but it's the chemistry behind it that's relevant to smaller engines and 2strokes in particular here
http://www.upmpg.com/tech_articles/motoroil_viscosity/
If you're still with me after this, well done.
It's a lot to take in i know
THE SHORT ANSWER:
In the good 'ol days when oil was simply refined a bit, cleaned a bit, poured into metal containers and called "motor oil", we took it for granted that the manufacturers had already done some research to make sure it would be compatible with different engine types with the current thinking and technology of the day.
Back then, if it worked well enough it was thought of as "acceptable".
With the benefit of hindsight we can argue that after several years of typical useage these engines might easily have some high levels of wear inside them, probably due to the type of oil used in the mix and maybe even questionable maintenance regimes. All of which will take its toll on an older designed engine with simpler designed bearings/bushes. Case in point with the dear old seagull engine.
Nowadays things have moved on. MASSIVELY. It's left that old skool thinking in the dust by comparison.
Chemistry and lab technicians take this stuff very seriously, finding new ways to improve "old thinking" and subsequently blend newer oils and ingredients to be even more competitive (or should that be more sympathetic) with older designs of engine.
For those of you that insist on using mineral oil in their seagull, great. Carry on. It's what they were designed to use in the first place.
For me though,there is a better choice. I consider conservation/preservation a bigger issue. That is to say preserving older crankshafts and reciprocating parts by better forms of lubrication. (not tree hugging
)Modern oils often out-perform older oils. It's that simple. Older engines will happily run with modern equivalent oils even when their originally designed specs clearly stated otherwise. It's all in the chemistry behind the label on that bottle of oil.As always the camp will be divided, i understand that. Some of you will never be swayed. I understand that too.
Jon
