burnsie
CB750 Member
Got a buddy telling me only use real oil but bike shop recommending full synthetic for old bike. 1978 cb550. I've run only real stuff but curious about pros and cons (if any).
Many thanks.
Many thanks.
Petroleum or synthetic?
- Thread starter burnsie
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- engine maintenance sohc
The problem I have run into on these old sohc hondas is the starter clutch seems to slip with synthetic. The problem gets really bad if the parts in the clutch are getting worn. Even with new rollers and springs I have still had issues. I try to run Amsoil in all of my bikes but I have ended up going to Valvoline motorcycle oil or Castrol GTX automotive oil in the old sohc bikes. Amsoil is safe with the engine clutch but some synthetics will make the engine clutch slip. I would probably recommend staying with a motorcycle specific convention oil and stay away from the full synthetics in the old bikes, just personal experience.
amc49
CB750 Guru
From what I've seen it's the magical 'friction modifiers' they used to replace the zinc they removed due to EPA regs, and it can even happen with conventional oil in some cases. The stuff is now TOO slippery and the OWCs used on these starter drives hate that stuff. I personally think some of the syn technology is slipping into standard non-syn oils now but don't tell anybody that. It could explain how I can go much further in the OCIs that I used to on my cars, the oil just never seems to burn like it used to.
Just for the record, I use cheap crap Walmart Supertech conventional oil in all my cars and now up to 9000 miles OCI now with zero problems. That ain't normal, at least it used to not be.
Use motorcycle specific JASO rated oils like the Valvoline mentioned, it still has some zinc in it but you'll pay the price, zinc oils went WAY up in price to forestall its' use in cars. EPA only allowed for small amounts of the zinc for 'specialty applications', why the bikes can still use it.
OP listen to your bud in this case. FYI, I have the same Walmart conventional oil in straight 30 weight in my '77 CB550F and it works fine. Getting hard to find that weight now though, it is no longer stocked on the shelves.
The slicker syn oil can definitely mess with your starter drive if it is right on the edge of not working, they don't tolerate much real wear at all before they begin to slip anyway.
Just for the record, I use cheap crap Walmart Supertech conventional oil in all my cars and now up to 9000 miles OCI now with zero problems. That ain't normal, at least it used to not be.
Use motorcycle specific JASO rated oils like the Valvoline mentioned, it still has some zinc in it but you'll pay the price, zinc oils went WAY up in price to forestall its' use in cars. EPA only allowed for small amounts of the zinc for 'specialty applications', why the bikes can still use it.
OP listen to your bud in this case. FYI, I have the same Walmart conventional oil in straight 30 weight in my '77 CB550F and it works fine. Getting hard to find that weight now though, it is no longer stocked on the shelves.
The slicker syn oil can definitely mess with your starter drive if it is right on the edge of not working, they don't tolerate much real wear at all before they begin to slip anyway.
amc49
CB750 Guru
FYI, the one thing syn oil is much better at than conventional is that it holds up far better at high temperatures than the old school stuff did, and that's a boon to air cooled bike motors. But it ain't spit if it makes the starter clutch begin to slip on you. Once they start that you are whispers away from the clutch doing it all the time, it's somewhat a self induced problem. You don't wanna go there.
As well, syn oil can soften some seal materials up to begin leaking at seals that didn't before with standard dino oil. No sense in asking for that either.
As well, syn oil can soften some seal materials up to begin leaking at seals that didn't before with standard dino oil. No sense in asking for that either.
dgreenbluet
CB750 Member
I use the cheapest oil I can find on my 72 CB750, and here's my logic behind it....
Think about what kind of oil was being produced in the 70's back when these bikes were produced. Even the cheapest oils these days are miles ahead of those grades of oil from the 70's and 80's. I think the dealer is just saying the generic answer and trying to get alittle more money from you.
Think about what kind of oil was being produced in the 70's back when these bikes were produced. Even the cheapest oils these days are miles ahead of those grades of oil from the 70's and 80's. I think the dealer is just saying the generic answer and trying to get alittle more money from you.
amc49
CB750 Guru
I agree. The people who push the higher priced product do it for a reason and commonly it's not in your best interest. While modern oil is fantastic porduct, I find it very hard to believe some of the prices asked for out there like Royal Purple and matching brands. That stuff has gone way stupid with people just like silly things like what older Splitfire spark plugs did to bring up the average price of spark plugs while doing nothing real world at all other than good old fashioned wallet draining. Now it's worthless E3 and Bosch+4 plugs, same thing. Gimmick.
Now with the cars it's fuel saving syn oils that are down around 5 weight and I'm thinking there's something there a lot more darkly insidious than simply saving fuel. My view is leaning toward the fact that most cars now properly taken care of can go 300K miles and if they don't you didn't take proper care of it. Meaning the OEMs are not selling nearly so many new cars as before, so they create 'fuel saving' much thinner oils to make you think you have to have them and then the cars wear out faster on the thinner oil. I have way more than base evidence to support that thinking too. So far I have kept up with the math and buying the cheaper thicker old school oil is at a $5000 credit to me for not buying the higher priced oils over 10 years and 2 cars. The easiest 5 grand I ever made, I lifted not a finger to get it.
Now with the cars it's fuel saving syn oils that are down around 5 weight and I'm thinking there's something there a lot more darkly insidious than simply saving fuel. My view is leaning toward the fact that most cars now properly taken care of can go 300K miles and if they don't you didn't take proper care of it. Meaning the OEMs are not selling nearly so many new cars as before, so they create 'fuel saving' much thinner oils to make you think you have to have them and then the cars wear out faster on the thinner oil. I have way more than base evidence to support that thinking too. So far I have kept up with the math and buying the cheaper thicker old school oil is at a $5000 credit to me for not buying the higher priced oils over 10 years and 2 cars. The easiest 5 grand I ever made, I lifted not a finger to get it.
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