Triumphrat

thirdbike · 04-08-2009, 06:41 PM

I am completing a bottom up rebuild on a '76 T140 and after having cleaned the sludge trap I am thinking that the stuff removed from there can't be a good thing. Surprisingly, I couldn't find any history of of a discussion on the use of synthetic oil.

I was wondering what if any experience and comments you might have on going synthetic in one of these old classics? They actually seem to recommend synthetic in the new Triumphs. Anyway, I already have an oil filter installed. I did some reading to discover that not all synthetics are the same. Actually, it was pretty interesting reading with several articles claiming Amzoil exceeds everyone else's performance including that real pricey Harley Davidson oil. They claim better oil pressure, viscosity and corrosion protection, as well as, less sheer and scarring. Just so you won't think this is a sales pitch, I won't post any links Although some naysayers warn about clutch slippage, I don't think it should a problem as I've used automatic transmission fluid in the primary and the clutch worked like a charm. There's nothing much more slippery than tranny fluid. I hope to defeat any oil seepage by switching to an improved gasket compound.

This do or don't discussion has been a hot topic in the general automotive world. I can still be swayed...

jimmy bush · 04-08-2009, 09:38 PM

You're going to get both sides on this one. If you like synthetics, use them, but unless you've stopped up the three transfer holes in the crankcase and installed a crank seal in the left case, your engine oil and primary oil are shared on your bike. If you put ATF in the primary it eventually was replaced by oil from the resevoir. If you use synthetics, don't use the extra slippery stuff or your clutch will slip because the engine oil is shared with the primary.

Beemie · 04-08-2009, 10:24 PM

I tried synthetic a few years ago.
I'm convinced that's when my first leaks started since the Bonne was new in '76.
Same thing on my '89 BMW auto; leaked past the seals like a fountain.
Now my thoughts are if the manual doesn't suggest it, don't mess with a good thing.

Let us know how it goes.

DAGAD · 04-09-2009, 02:11 AM

Hi Thirdbike, as Beemie says......... use a good quality SAE 20/50 mineral oil and the ATF in the clutch. DO NOT over fill the primary, better to have 1/2 ounce less than too much. While there might, perhaps be a small transfer over time, don't worry about it. More importantly, get a motorcycle specific engine oil if you can. I would recommend a 70/90 semi synthetic for the gearbox.
Roy.

GrandPaulZ · 04-09-2009, 09:21 AM

I use Castrol GTX and other Castrol products, almost exclusively, unless directed by the client to use something else.

Germ · 04-09-2009, 12:38 PM

I wouldn't run synthetic unless I had an oil filter on my bike.

thirdbike · 04-09-2009, 12:51 PM

I am really curious now why everybody so far is set against using synthetic. Other than the leakage potential what else nixes this switch? I was talking to a buddy who used to race stock cars. He says his engine (the coolant) ran 15 degrees cooler with synthetic and runs it in all his 4 wheeled vehicles and his new Kawi.

Beemie · 04-09-2009, 01:07 PM

Not against synthetic if the vehicle seals were designed for it.

But then again, even some of those suffer; our vette's rings never seated; It came with Mobil 1 from the factory.
Apparently lubricant can be too slick.

Probably sooner or later we'll have a limited supply of dino and the synthetic will cost less and the tides will shift.

Germ · 04-09-2009, 01:07 PM

Since i don't run an oil filter I stay away from oil that contains detergents. Plus I'm cheap

DAGAD · 04-09-2009, 02:24 PM

Firstly, GOOD advice from GPZ. You won't go far wrong with Castrol GTX 20/50. Next, Germ, Cheap is not always bad......... there are some good cheap oils out there. Look for one with an API SH or better. If it's cheap, change it more often.............. Oil does not break down, it gets contaminated.
So, on that theme of contamination, using a synthetic on our old engines with large tolerances, air cooled and often not equally air cooled, blow by from pistons, valve guides, etc. do not work. They were designed in the 1940's and the engineering is from that period.
Mecchanica will tell you other wise and I believe what he says. However what he does not tell you is how well he prepares a motor or the time spent measuring and generally blue printing......... THIS IS the secret. Running an old engine on new synthetic oil will not give good results. Honest, oh yeah and it is VERY EXPENSIVE.
Roy.