Engine Oil

[Andy_C]

OK Oil threads can be contentious, but going to ask anyway.

What is the general opinion about engine oil for a 3 1/2?

Manual says GTX so that would be 20/50 so guessing any 20/50 would do the job.

Have seen some suggestions that semi synth 10/40 is the way to go, or even 20 / 50 semi synth.

Reason for asking is that I dont know when the PO changed the oil in the bike I bought late last year, so to be on the safe side think it sensible to change it.

Thanks.

[George 350]

As you say, there are 10w40 and 20w50 advocates in the Morini world. I'm in the 20/50 group and bike is currently at 98000+ miles, never used synthetic oils either.
More important is to change it regularly as the filtration is very basic - for most of its life, I've used 1500-2000 mile oil change intervals.
As for brand, realistically any decent one will do, you don't even need to have Jaso MA2 spec as we have dry clutches.
For what its worth, I'm currently running Motul 3000 20W50 as I got a good deal on it.
Hope this helps,
George

[MickeyMoto]

I used to use 10/40 semi, but now use 20/50 mineral oil as used in my plain bearing BMW. Although both grades cover most temperatures here I find during warmer weather the 20/50 performs better. Motul is the oil brand I use.

[70sbikes]

I use Penrite MC4ST 20W-50 motorcycle premium mineral oil. It has "FULL ZINC MAXIMUM PROTECTION". My 1979 Honda CBX gearbox is the smoothest it's ever been with this oil. I noticed other oils I had used for years steadily reduced their zinc levels.

[Andy_C]

Well it does say to use 20/50 so that is what it will be.

Motul seems readily available in the UK unlike Penrite.

[3potjohn]

Ah the old zinc topic beloved of us owners of airhead clunkers. I have been using semi synthetic 10w-40 in my Sport since 2007. I use 20w-50 in my 501 as it seems to run a bit hotter.
I have used Morris 4T Race ( or whatever it is called)if I can it cheap enough. Now expensive.
Main thing is avoid short journeys and change at a suitable interval.

[funsize]

As always many different ways of skinning the cat. Only had the bike 5 years but always use Putoline DX4 10/40, they only make bike oil and it’s their more basic semi with around 30% synthetic. As I only do around 1-1500 miles a year I lay up in winter with fresh oil so the nasty contaminates can’t work away at things and change it halfway through the season. Maybe a bit over the top but compared to engines, oil’s cheap

[Andy_C]

Did the oil change, used MOTUL 3000 20/50 best price I found was from Opie Oils, so bought 5 litres, enough for 2 oil changes.

That particular oil seems freely available and a decent spec - I did have a can of Comma 20/50 oil in the back of the garage, but thought better of using it as there are no specs marked on the can, oil is cheaper than an engine..........

The stuff that came out was not nice, really should have changed it before I started riding it, anyhow, all done now.

Think I may have also found the source of the oil weep, the drain plug had no sealing washer on it - so I think that oil may been seeping out and getting blown to the rear of the cases making it look like a weep from the rear of the engine, will find out when I next ride it.

[MickeyMoto]

I can never get a good seal on the oil drain plug. There is a paper washer for it. A smear of oil goes a long way, you may find there is oil around the breather, another area which I find hard to control. Maybe it is just me!

[Andy_C]

I ordered a couple of drain plug seals from Mdina and they are copper and not paper, the mating faces looked free from any damage so just wiped the mating faces and assembled dry.

IMHO copper sealing washers usually work well unless the mating faces are damaged, or the copper washer is not in the soft state.

I also have a little mist around the breather, nothing to be worried about though.

[MickeyMoto]

I often wonder why Morini went to paper washers, anybody know?

Perhaps it was a money thing.

[3potjohn]

I seem to have a drain plug with a flange and a copper washer. I anneal the washer, clean it all up and a thin wipe of threebond on it. No leak ever.

[Andy_C]

Yep the drain plug on mine is a big brass plug with a flange.

Back in my Triumph days I was used to annealing copper gaskets / washers, still do it with the copper head gaskets on my KH 400.

I was surprised the Morini draing plug "sealed" so well without the copper washer. No sign of any weeps yet but then again have not ridden it to get the oil nice and hot since fitting it.

[FatherB]

I found that my original brass drain plug was a quite tight fit. As it was a bit chewed up on the hexagon I replaced it with a new steel one from NLM which was also quite tight. I drilled a blind hole in the centre through the threaded section and Araldited a magnet in there to catch any metallic particles. Originally they had a thick paper washer but I use a good fitting copper washer. I always anneal even new copper washers as the manufacturing process can make them quite hard. That softens them nicely. Heat to cherry red with a gas flame and quench in cold water. Then clean off any residue with some fine steel wool and clean with brake cleaner or white spirit. 'Dowty' bonded washers are also excellent for drain plugs.