what oil to use?

[reef5000]

hi I would like to know what oil to use in 1974 cb 750 k.I have download manual but fail to locate exactly what sort of oil.It call for 10w40,but it is motorcycle oil or dyno automotive?I do not want to use synthetic.Thanks

[TOOLS1]

I use Texaco Havolin 10w 40 in all my bikes, and change it every 3000 miles. I used to be a professional mechanic, and have torn several engines apart. I would always ask what kind of oil they were running, and the cleanest engines always had Texaco Havolin in them.
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[reef5000]

yes thank you.Does have to be for bikes like 4T or just automotive regular?

[bijna]

I use Shell rotella is almost everything. It's meant for diesel engines I think. Its great stuff and it's meant to take a beating.

http://en.wikipedia.org/wiki/Shell_Rotella_T#Motorcycle_usage

[TOOLS1]

Just automotive is fine. The big thing with oil is to change it regularly. I know a lot of people are running the Rotella, but I have seen the high detergent oil eat up aluminum engines. Also the Honda engines do not run anywhere near as dirty as a diesel engine.
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[Thorby]

I used Quaker High Mileage oil for cars in my last change and my bike has actually behaved better since it no longer puts out white smoke during the first minute of having being cranked cold.  Gas mileage has been good at 43 mpg.  I should mention that my winter has involved cold morning cranking in 40 degree weather.  I can't recall the actual viscosity of the oil, it's thicker than what the manual calls for.  However, this oil is very easy to find in any auto parts store, it's the one in the red container, so you can look at its viscosity in your next trip to the Autozone.

[Thorby]

I agree with TOOLS.  Regular oil changes are a higher priority for me than spending big money on "special" or fancy bike oil.

[Piute]

                                                                   
                                                         I agree with TOOLS.
                                        Regular oil changes are a higher priority for me
                                   than spending big money on "special" or fancy bike oil.
                                                                   

[TOOLS1]

I hate to tell, you, but the dirtiest, nastiest, and gummy engines I have ever worked on were running Quaker Cake oil. Irony is my Dad used to use the crap. After I got his 85 S-10 from him, and switched it to Havoline it was, so gummed up it would only hold 5-10 pounds of oil pressure. Had to drop the oil pan, pump, and pickup off to clean them. They were plugged tight with gum, and goo. Quaker Cake, and Arco are the two oils I would never use. Not even, for free on a dare.
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[sgtslag]

If you want to know, for certain, what is going on inside your engine, and how well your oil is performing, spend the money on oil analysis (~$20-$30).  Otherwise, any SAE oil rated "SM" is fine, as long as it is changed appropriately.

If you want to be sure your engine is clean, buy a can of SeaFoam Engine Oil Treatment, and follow directions for adding it to your engine oil.  It is mostly white oil, along with some other chemicals.  It is 100% petroleum products, it will not harm your engine, but it will dissolve gum, varnish, and carbon deposits.  Once your oil turns black (if it turns black...), change it, and the filter, as this indicates that it has dissolved a load of junk which you want to remove ASAP.  When I treated my K model, it turned the oil black after five minutes idling on the center stand, having just reached operating temperature, 180 F.  I treated the same engine, 5,000 miles later, and after 300 miles, my oil was still the same caramel color -- no deposits, no gum, no varnish, no carbon.  After treating your engine, you can start with the oil of your choice, knowing that your engine, and transmission, are squeaky clean.

There is a growing body of evidence that engine oil will last around 7,000 miles, due to improvements in both oil chemistry, and engine technology.  Again, the only way to know, based on facts, as opposed to supposition and guessing, is to burn the cash on analysis.  Unfortunately, I have not hit the mile mark where I can send some oil off.   I hope to do my first analysis this Fall (synthetic oils last twice as long as regular, if not more).  Another characteristic of synthetic oils, is viscosity:  Shell Rotella T6 Synthetic (SAE rated SM, for automobiles; rated JASO MA for use in motorcycles) has a viscosity of 5W-40, so it is really easy to turn over an engine at 0 F -- love it for my vehicles here in Minnesota.  I switched all of my engines to the Shell T6:  one oil to stock, one oil to use, in everything requiring oil (one car, one truck, two motorcycles, two lawn mowers, one snowblower, one air compressor).  Cheers!

[Re-run]

I use shell rotella t6 5-40 in all my bikes. You can use a standard 10-40, I used to. If you live in a hot area, a 20-50 works too. But the different in engine smoothness, shifting ease, and oil chain intervals more than made up for the slight additional cost. The biggest cause of engine wear in motors like this is lack of zddp. Engine oils of old 60 days had good doses of this stuff. Standard motor oil these days does not because it wreaks havoc with catalytic converters. Diesel oil such as rotella has additional zddp in it. Yes it has more detergents but not enough to cause damage, after all, a lot of new diesel engines have aluminum in them nowadays and this oil is very popular.

Do not shy away from synthetics. Synthetic is superior in every single way. It flows better when cold. It has a higher flash point and holds it viscosity better at higher temps. It protects better than any conventional oil, even in these engines. I switched to it in mine and I would never go back.

Do not cling to the old days when synthetic was considered bad. This is no longer true. And cost is not much different. A decent oil such as castrol is 2.50 a quart, if not more. This stuff is about $4.
$4 for longer oil life, better protection, plus, almost every new car, truck, whatever, uses conventional from the factory.
Whatever oil you do use, make sure it is a decent oil and look on the back to make sure it does NOT say "energy conserving".

[Cabreco]

I use Shell rotella T Triple as well. and if it hasn't been done I'd do a Seafoam treatment on the crankcase. You would be amazed not only at the gunk that comes out, but at how clean your next oil change will be. I also found that the bike runs cooler after the Seafoam.

[TOOLS1]

Where can I get Castrol, for $2.50 a quart?
TOOLS

[shinyribs]

I use Rotella in everything but the Impala,my highway car. it gets right at 2 mpg better using Mobil1 full synthetic. I use the Rotella truck oil in my Duramax and every race engine I ever had. I was getting 500+ passes on bearings vs my buddies 3-400 who were using the latest "race oils". Duramax has 260k on it and I ghange the oil every 6k miles. It is still yellow at 2500 miles,so I stretch the changes out longer.I have been using the Rotella that Sarge recommended in my bike.All good so far. We had a E-350 with a 351w that Dad demanded we use quaker state in. It didn't end well.

[Re-run]

I can get it at walmart, but it is not synthetic.

[LukeM]

I have read on other forums that the Energy Saving feature of most automobile motor oils will play havoc with the clutches on the CB750 style motorcycles. Rumor has it the extra slippery stuff in there will cause clutches to lose their clutch-ability (if that's such a word). I've used MC specific 10w30 in my old bike, and I'm currently running Rotella synthetic 5w40 in my Shadow. There _seems_ to be a slightly easier clutch/shifting feel compared to the dino-type oil, but that may be subjective on my part.

Luke M

[james1963]

my father has a 1971 CB 750 k and he's always used 20w 50 caster oil motorcycle, cause of the heat they put out, and he said stopping and waiting at red lights they build up a lot of heat and the heavier oil keeps the motor cooler at all times ,but in winter months takes a little more cranking cause of the thickness,

[Re-run]

In hot climates, especially years ago, this was the way to go. Areas in the south mainly. Up north where the temps don't normally get as high, 10-40 was usually better as our mornings are usually not that hot and 20 weight can get pretty thick.

These days, with the good synthetics that are easily available, 20-50 isn't really needed any more. Nut if you do elect a 20-50, a synthetic will be better than conventional.

[james1963]

20 w 50 in the south, do not use  synthetic on a old motor unless you want to rebuild that engine, if you live in cold climate up north use an oil stick warmer, on 20 w 50, remember ive had this 1971 Cb 750 since new and never rebuilt runs great,

[Re-run]

That is actually an old wives tale that somehow still lives on from the initial days of synthetic. Fact is, the only time synthetic will cause that to happens is if the motor already needs a rebuild. It cleans the sludge left from bad oil that has collected on the seals and then those seals that were bad anyways, start to leak.

While I have not had my k8 that long, I have had it 20 years. I would never use 20-50 in my area. Especially when I ride in 40 degree weather commonly. I started with 10-40 and used it for a few years. Switched to rotella 15-40 and ran that a while. Switched to rotella 5-40 and haven't looked back. Shifting is excellent and oil life is better than conventional could ever give. Wanna know my leaks? The typical left side leak that happens regardless of oil used. The leak that is actually only a slight weep. Most people just stick a piece of cotton rope there to soak the oil up till it gets bad enough to pull the engine.

I didn't have a single clutch problem or any other problem switching to synthetic. And synthetic has worked perfectly fine for many other cb750 owner. I also switched to synthetic for my 84 v45. No problems to report there either. Indeed, I will probably have less cam issues than with conventional oil.

However, you are free to use what you want. If it works for you, there is no reason to change. The old synthetic oil myth is just wrong though. It does not cause a problem, it only reveals problems that exist.