synthetic oil pros and cons?

[slash360-2]

 1981 cb750 C. I'm thinking about switching to synthetic oil,I've been using pennzoil,or valvoline 20w50.I cant find Mobil1 or Royal Purple in that weight,are synthetic weights different than standard? Your opinions would appreciated. Thanks Steve L. in N.C.

[Re-run]

Oh here we go!
Oil is a huge topic. However, I run synthetic and it is proven that synthetic provides the best protection.
There is a lot of myth information against synth but most of it is from the 70s and 80s and no longer applies.
The weights can be treated the exact same BUT in cold weather, synth does not thicken up like "dino" does. That is a good thing.
Synth CLEANS your engine out. This is good BUT if you have a lot of sludge, that sludge will get moved and all sorts of things can happen. Now this is not a fault of the synth, it is a fault of conventional oil that left the sludge in the first place. This sludge can goop up your clutch and you have to pull it apart to clean the plates. it can also plug the oil lines in the heads and cause oil starvation. That sludge also seals up poor oil seals to an extent so once it is removed, leaks could occur.
Again, this is not a fault of the synth oil but of the conventional that was used.

In my 78, I used regular 10-40 for a while. Then moved to rotella T 15-40 for 2 changes and then jumped on rotella synth 5-40. It is a diesel oil and has worked very good. I got ZERO leaks or any other issues.

I know some people are going to say use a bike oil but if you follow the manual guidelines, you are just throwing your money away. it is your bike though.

[brcree]

I agree with rerun.............I have a 85 Goldwing that had trans gears whining so loud! The bike sat along time.  I went with am soil and within 50 miles I couldn't hear a whine! No kidding. The bike shifted easier, ran cooler. I also have an 07 vtx 1300 that had valves so load that I almost sold it! Put Amsoil in BAMB....95% noise gone. Vtx's are bad for this valve clatter.  About the sludge, if your bike has some age on it run some engine flush first then go with synth. If the price bothers you do the home work and see how you really save money and your bike will run better for it!  Hope this helps.

[swiffer]

Good topic.

[Re-run]

If you want to see one of the fine points of synth, put some conventional in a jar and some synth in a jar and put both in a freezer for an hour. See which one pours better. Unless you got a super cold freezer, the synth will pour better.
Another one is to use conven in your lawnmower and change it and then do the same with synth. World of difference usually.
just neat things to try.

[slash360-2]

Thanks for the tips guys. I 'm going to give the synth a try.What weight would you recommend, I've been  using 10w/40 or 20w/50 conventional.Most of the synthetics I have seen have a 5w#? Thanks again for your help.

[Re-run]

Depends on the heat in your area. If you do a lot of sitting in traffic on hot days, a 20-50 would be very good. otherwise a 5-40 would be excellent. Just make your you check the starburst on the back and make sure the oil does NOT say "energy conserving" on it.

[Polymer-2]

Synthetic is almost always better. Just don't use it in a fresh rebuild until the rings have time to seat.
It reduces friction so well that new rings won't seat well unless special honing techniques are used.

On the lawn mower example never use a detergent oil in an engine without an oil filter. I don't know if there is a non detergent synthetic (although there probably is) but you want a non detergent oil in most small engines.
The reason is the detergents keep the contaminants suspended in the oil so it gets carried back to the filter where it is removed. On engines without filters non detergent oils allow the contaminants to drop out into the bottom of the crankcase rather than recirculating back into the moving parts. That way the contaminants are removed during an oil change (if the engine is warm). Look at the sludge in the bottom of the next small engine you disassemble.
This is also the reason you never want to use racing oils on a street engine or you will wind up with excessive sludge. Most (true) racing oils are non detergent because many racing engines have high pressure and high volume oiling systems and don't use a filter. These engines are torn down every few races and cleaned and inspected. Also detergents tend to foam under racing conditions which aerates the oil.

[Re-run]

Lawnmowers work just fine with synth. Again that would be old info no longer applicable. Many mowers allow the use of synthetic now. Same with most any small engine now.

[Polymer-2]

re-run wrote

Lawnmowers work just fine with synth. Again that would be old info no longer applicable. Many mowers allow the use of synthetic now. Same with most any small engine now.

It's not the synthetic that's the problem. It's the detergent additives.

[hocko]

No dont from my experience i used semi syn and it found its  way out and i went 50 miles and i had oil over my feet! So i went back to cheap 10/40 form a hypermarket and no more wet feet. I know a guy how uses 20/50 in a old 500/4 Syn was not about when these engines were made. I would be intrested to know what the outcome is. Good luck  Ian (uk)

[hocko]

No dont from my experience i used semi syn and it found its  way out and i went 50 miles and i had oil over my feet! So i went back to cheap 10/40 form a hypermarket and no more wet feet. I know a guy how uses 20/50 in a old 500/4 Syn was not about when these engines were made. I would be intrested to know what the outcome is. Good luck  Ian (uk)

[Polymer-2]

I have a friend that is a petroleum engineer and I sent him an email asking his opinion. I'll let you guys know what he says when I hear back from him. May be a little while. He travels extensively.

[Polymer-2]

He got back quicker than I thought he would. He basically said that it's ok to use it in small engines just change it more often.
Here is his quote:

I don't know why you couldn't use synthetic. We use them all the time in go carts. I think the main issue with things like a lawn mower is that changes should be at least once a season, where for most people that is only 20 to 30 hours of operation.
The only arguments I've seen for non-detergent in old equipment is the thought that it will clean up the insides and cause problems, which is only partially true. at some point most of those engines have been repaired, and those that haven't need cleaning up one way or another. The chance of dislodging too much carbon at once with a good CI-4 is minimal.
If you really want a synthetic non-detergent, look for a PAO compressor oil.
Richard

[Re-run]

Ian, that issue is caused by bad seals. Regular oil builds up around the seals and acts like a barrier. Synth does not do that. If you had good seals in there, it would not leak. I have an old 1978 cb750 and it has never had the seals changed yet and it does not leak when using synth.

[hocko]

thanks for the reply it seams strange how the oil effects the seals and now its ok. safe riding!!

[woodsrider250-2]

It's not really the detergents, but rather the friction modifiers in most modern oils, dino or syn, that you want to stay away from.  Great for motor, bad for wet clutch.  Generally, presense of friction modifiers is noted on the bottles EPA stamp as being 'energy conserving.'  Say away from oil with that designation, dino or syn, and you'll be OK (been my experience).  You'll never find a 'motorcycle' oil that says energy conserving on it.

[Re-run]

Actually I think you will. See not every bike has awet clutch and for those, that is probably the specified oil. But that does not pertain to any 750 hondas that I know of.

[woodsrider250-2]

Dry clutch bike run whatever the heck you want.  Plusses and Minuses to dry clutches, this being a plus.  :)  I've never seen a 'dry clutch motorcycle oil'  Maybe ducati makes one, that's most likely re-labed car oil.  All 'Motorcycle' '4-stroke motorcycle' '2-stroke gearbox' oils/etc will never be "energy conserving" is all I'm saying....So I've always bought cheaper oil (dino or syth) that isn't labeled as such and have NEVER had an oil-related wet clutch problem.  I've seen plenty that didn't heed this and did have problems.  Only CB that would be dry clutch would've beena  works-type racing conversion.  Another plus to dry clutch is 2min clutch pack changes.

[cbRider]

I've been using Castrol Tection Heavy Dudy Diesel Motor Oil 15W-40.
It will definitely hold up under extreme conditions.
You can get it at Walmart. It seems to do everything well for me.
 
Karl