Topic: Does Synthetic Oil Cause Oil Leaks?

[736cc]

An excellent running 45,000 mile K1 I just picked-up on has a couple of odd oil leaks- the oil galley screw-on plug above the points cover, and the oil pressure sending unit above the starter. While rummaging thru the po's receipt papers, a tune-up shows semi-synthetic oil used.  Any oil opinions?
Interesting thing about this K1 is the fact that I used to own it about 6 years ago; went thru a couple owners since, and its back home, completely unchanged. Found it on Craigslips.
And oh yeah- the clutch slips.

[fantino]

As I understand it, synthetic oil particles are smaller and more uniform than Dino oil, hence why it transfers heat more efficiently. Synthetic oil doesn't cause leaks, but is better able to leak, if that makes any sense. I think the factor by which this occurs compared to Dino oil is pretty low though. Someone feel free to correct me if I'm wrong here.

Evan

[Jerry Rxman Griffin aka MuthaF'er]

Put in a new o-ring and tighten down the cap. Screw in the oil pressure sending tighter &/or teflon tape it. Does the tune-up show they used motorcycle specific synthetic? Oil doesn't cause leaks, it's what is leaking.

[Frostyboy]

This appeared some 5+ yrs ago.......

http://forums.sohc4.net/index.php?topic=416.0

 

[grumpy]

This appeared some 5+ yrs ago.......

http://forums.sohc4.net/index.php?topic=416.0

 

[Gordon]

Define "cause"...






Wait, no!  Define "does"...

[rbirkhan]

Dont use synthetic oil it will glaze your clutch. Dont ask how I know this. Its so slippery it causes the clutch to slip and eventually the discs  get glazed and will require replacment. Oh and yes the molecules are smaller and if you have leaks it will leak more. Friction wise synthetic is way better but with a wet clutch its a no no.

[MCRider]

This appeared some 5+ yrs ago.......

http://forums.sohc4.net/index.php?topic=416.0

 

Well... convinced me!

[funkdr5]

synthetic is thin, try a heavier weight dino. you can switch back no prob.

[lone*X]

Agreed, the synthetic isn't the problem with the leaks, old gaskets/orings are.  Slipping clutch is probably the oil.  Never use any oil that contains friction modifiers with a wet clutch.  If after you fix the leaks you still want a synthetic, Mobil1 4T and Amsoil both are full synthetics that work well with wet clutches.  I currently use the Mobil1 in my VTX since it is more readily available than ordering the Amsoil but both are excellent.  I still use (and plan to use) Castrol GTX in my 550.  It has never had anything else in it.

When choosing any oil, just make sure it's not labeled "energy conserving" and does not contain friction modifiers like moly. 

[Skunk Stripe]

Dont use synthetic oil it will glaze your clutch. Dont ask how I know this. Its so slippery it causes the clutch to slip and eventually the discs  get glazed and will require replacment. Oh and yes the molecules are smaller and if you have leaks it will leak more. Friction wise synthetic is way better but with a wet clutch its a no no.

None of what you said is true as far as being caused by synth oil. If this happened, something else caused it. Something such as a dirty engine which got cleaned out by the additives in the synth oil. OR you used the wrong oil.
I switched to rotella synth 5-40 and I had neither leaks nor any sort of clutch issue. Many have switched with no issues. Most leaks are caused by potential leaks plugged by sludge build-up which gets cleaned out or by sludge in your oil which then gets mashed into the plates thus contaminating them. The other main cause is using the wrong oil. After all, honda hp-4 (i think) is a synth oil for use in all honda motorcycles.

[BobbyR]

Oh No, the dreaded O thread.  

[wrenchmuch]

!!#@$$# I dropped my popcorn  .  HP4 Is semi synth . I ran it and wasn't impressed with the way my tranny worked ( hard shifting ) . HP4S is the full synthetic version
. Using AMSOIL 20-50 right now . Great oil IMHO . . Maybe we can get a cooler thread going too .

[Skunk Stripe]

My point with hp4 is that it is fully acceptable to run it in all honda motorcycles thus really proving that synth is not bad.
The negatives of synth come from the old days when it first came out in mass quantities.

[Markcb750]

Love that rant on synthetic oil, classic.

[bjohnsonassoc]

In the 90s Honda racing used regular oil to break in their engines, then switched over to synthetic, no clutch problems, no leak problems. I think they probably know more about oil than anyone on this forum ever will.
There are two types of Honda CB motorcycles, those that leak oil, and those that are going to leak oil.

[Terry in Australia]

I think Skunky is right, people are confusing synthetic oil with friction modifiers, two entirely different things. Most motorcycles have oil bathed clutches nowadays, and work fine with synthetic oil. Anyone who tried the old Castrol GTX with friction modifiers in a CB750 in the early 1980's like I did will know what that does to an oil bathed clutch.

Like Jerry suggested, fit a new O Ring Andy, and maybe some teflon tape to the thread on your oil pressure switch, and it'll be fine. Cheers, Terry.

[bjohnsonassoc]

Dude you are everywhere!!!!!

[Terry in Australia]

Are you following me? Let's play thread tag!

[bjohnsonassoc]

You'll win, its getting late here.

[Ichiban 4]

Here are three things from my experience in using synthetic oil:

1.) Several Honda certified mechanics I know..recommend against using FULL synthetic in these old SOHC 4's. Semi- synthetic is not as bad they say..but if the bike has basically been run on regular petroleum oil for most of it's life..better to stay with regular oil.  2.) on my bike..it leaks more on semi-synthetic than on regular Honda fossil oil. 3.) from a purely chemical point of view..if the oil molecules are smaller in synthetic than in strictly petroleum based oil..it will tend to leak by gaskets..O-rings easier.  This is also one of the reasons we go to heavier viscosity oils in engines that are worn/have looser tolerances after many miles.

In a slightly different perspective: I've run full synthetic oils in some of my reciprocating equipment (air compressors..vacuum pumps..et al..for years/decades..and it definitely leaks a lot more around gaskets..etc..than with petroleum.  BUT..the equipment goes a lot longer between servicing..because of superior lubrication and cooling properties..I surmise.

So..one question seems to be: do you want a leakier..messier piece of equipment that runs/lasts longer?  Or do you want a cleaner piece of equipment that either needs more frequent maintenance..or doesn't last quite as long?

Some comments from personal experience..over the past 30+ years or so.

Al / Ichi

[Skunk Stripe]

The leaks and such though indicate already worn gaskets and such being temporarily sealed by oil sludge. So as for a cleaner engine, ONLY if your seals are bad enough to leak oil in the first place and what about the inside. If you put in synth and things leak, it was getting time for a rebuild anyways.

[Jerry Rxman Griffin aka MuthaF'er]

How about a high mileage synthetic without friction modifiers? Have we been over that before? I use high mileage dino oil in my 200,000 mile Legend about every 4th change to "condition" the valve seals that probably hardened when the thermostat went south and caused some serious overheating. It does cut back on consumption. Maybe it would expand the seal?

[Skunk Stripe]

Do you HAVE to use the high mileage? I have a mazda with 190,000 and use 5-30 mobil1. Not synth but not high mileage either. No leaks or consumption. Does yours use oil or leak? nice to own cars that can at least get that kinda mileage isn't it.

[lone*X]

Do you HAVE to use the high mileage? I have a mazda with 190,000 and use 5-30 mobil1. Not synth but not high mileage either. No leaks or consumption. Does yours use oil or leak? nice to own cars that can at least get that kinda mileage isn't it.

Mobile1 is synthetic.  Are you saying that you use 5-30 mobil1 Dino?