78 750F Oil Recommendation

[welovedon]

About to change the oil for the first time and wanted to know what oil to buy and can I run Full Synthetic on it?  Maybe a dumb question, but is there an oil filter and if so, where is it and what kind should i get?  

Thanks.

[Peterwh]

Yes, there is an oil filter.  It's that finned thing that sticks out and angles down at the front of the engine.  It has a large bolt goes through the middle of it.  You simply unscrew the bolt and the whole thing comes away.  You have to juggle it through the frame.  You also need to remove the drain plug to drain the oil tank and sump.  The drain plug is under the engine.  All of this is in the manual that you can find on the forum.

You can get new filters at several places on the Internet, including eBay.  I think they have them at www.vintagecb750.com

Regarding the oil to use, there is something of a debate about whether to use synthetic oil or not in these old engines.  I'm a great fan of Mobil 1 myself but I don't use it in my CB 750.  Personally I use a good quality 10:40 organic motorcycle oil but you need to take into account the kind of temperatures at which you are likely to ride.

[TOOLS1]

You can get a Fram CH6009 at most any auto parts store. They come with new O-rings. Be careful with the bolt. Several have been destroyed, by being overtightened. I use Texaco Havilion 10W-40 only. It is the cleanest oil I have ever used. I also change every 3000 miles.
TOOLS

[sgtslag]

  Any filter will do, as they are all pretty much the same (K&N have red colored filter media, and they claim to be better, but they don't specify how...    save your money and get the cheapest).  As for synthetic oil, I run Shell Rotella T6, which is billed as synthetic, but may just be a super-purified, dino oil.  Bottom line is this:  it is 5W-40 (very thin at low temperatures, spins over super-easy in January, in my car after being parked in a ramp all day, in sub-zero Fahrenheit temperatures); it has no friction modifiers to mess with your wet clutch; it is higher in detergent levels than conventional motor oil; I use it in all of my motors, including small engines, and motorcycles, so I only have one single oil type, and brand, in my garage; and it is SM/SL rated, so it is safe for automotive engines, even though it is a diesel oil, and it is $21/gallon, at Wal-Mart.

I've been using it in three bikes, for 2+ years:  1979 CB750K (up for sale); 1983 Kawasaki 440 LTD (sold this Summer); and a 1993 Kawasaki Voyager (main touring bike, two up, with heavy luggage load; 3,000+ miles thus far).  I've been happy with it so far.  I also run it in my 1975 Ford F100 pickup truck.  No issues in any of my vehicles.  Being synthetic, I also run it 7,000 miles in my bikes, and 10,000 miles in my four-wheeler's.  Planning to do oil analysis on the cars, and the Voyager, to see just how long I can run this stuff between changes.  Analysis is the only way to know for certain.

If you are concerned about using a "diesel" oil in your non-diesel vehicles, do an Internet search on Shell Rotella T6 oil and motorcycles.  You will find considerable comments on it, including other users' results.  It has been in use, in motorcycles, for many years, with good results.  It is inexpensive, excellent quality (if truckers did not trust it, it would have gone off the market decades ago...  if it weren't good, it would not be on the shelves of trucking stations, as no one would buy it -- check out how many brands of diesel oil they stock on their shelves).    Cheers!  

[shinyribs]

$21 a gallon?!?!   It was $12.99 last time i changed the oil in my truck

[TOOLS1]

When I had Chevy trucks. I just added it.
TOOLS

[welovedon]

I've been hearing good things about Rotella T6, namely for cars, but I'll check it out for motorcycles too.  Do they come in 10w-40?  I live in Orange County, CA and the temp. doesnt get really cold and gets to be okay hot (low 40s to high 80s).  

I download and read the "mechanics handbook" and it mentioned something about an oil screen?  

Oh and off-topic, but does anyone know of a link that can help me rejet my carbs if i change them out to pods?

THanks,
Don

[samir_nayanajaad]

I don't know much about these CB750 engines yet but I have done a bit of research on oils and filters.  Take this along with a grain of salt but for what its worth....

NOTE: after reading this I found that by trying to keep this simple I may confuse some people. When I am talking about oils being thicker or thinner than others keep in mind what temp I am referring to, start up or running temp. Also I posted a link at the bottom of where I got most my info from.

First some info on what 10w-30 means. Oil is rated by what grade it is (commonly referred to as weight)  The higher the grade the thicker it is. Usually measured at somewhere around room temp.  But the thing is the viscosity aka thickness of oil changes when it gets hotter or colder. This is a problem for engines because they maybe outside at 32 degrees then when they are warmed up they run at 180 degrees.  The oil is thick when cold causing low oil flow and when its hot the oil is too thin causing low oil pressure.  

Enter the multi-grade oils like 10w-30.  Cool thing about these oils is when its cold it acts like a 10 grade oil, in other words its thinner at 32 degrees than a 30 grade oil, but when your engine heats up it acts like a 30 grade oil, or in other words its thicker at 180 degrees than a 10 grade oil.  So you get thin oil on start up for good oil flow/pressure and when its heated up its not too thin.

The things that do the viscosity changing are called VI's.  They are one major reason to change your oil regularly. They break down and eventually your 10w-30 just acts like a 10 grade oil  (too thin at running temp causing low oil pressure).  Thing that breaks down the VI's mostly is heat, most conventional oils work ok up to 200 ish degrees (don't quote me on this been a while from when I read up on all this) this is why these bikes and other air cooled engines you had to stay on top of oil changes or you will damage the engine.

Now for synthetics.  More or less just think of them as super oil. They can be even thinner at start up and thicker at running temp than conventional oil (like a 0w-30 rating) and they can handle colder and hotter temps with out breaking down and they last longer.

Now the CBs were designed back when there was just conventional oils (not sure when multi-grade came out so they may have been designed to run on straight 30 grade oil maybe one of the other guys can comment on this) I have no idea what synthetics will act like in these bikes.  So far what I have read and others have posted is as long as there are no friction modifiers it will work ok.  That is great because synthetics can handle higher temps of the bikes so they dont break down means less oil changes.

Now onto filters, this is way shorter I promise.  More or less all filters use cotton or some fibrous material to filter particles out of the oil.  This filter can be very fine to grab every little particle that comes its way but this slows oil flow to a crawl as well as it gets plugged up fast. Alternately the filter can be very open allowing more flow but also allowing more gunk to float back into the system.  

Most Fram or cheap filters hit in the middle, balance between filtering and flow. They will work just fine on a daily driver as long as you change them on a regular basis with your oil.  Other more expensive filters like K&N are supposed to be the best of both worlds offering better filtration with better oil flow.

I have only read on the Mobil 1 filter that uses some sort of synthetic filter element that actually achieves this high flow and high filtration.

And if you want to know more than you should about oil
The Car Bibles page on oils

[sgtslag]

Who sells it for $12- something a gallon?!?!

The 5W only comes into play when the oil is cool.  Multi-viscosity oils change their weight/thickness with their temperature, becoming thicker at higher temperatures.  Rotella T6 thickens up to 40W as it's temperature rises, maxing out at 40W.

Another advantage to synthetic oil is it's breakdown temperature:  450+ F.  My '79 ran it's oil @ 250 F, when it was air cooled (OEM set-up, now with an oil cooler installed, oil runs @ 210 F) -- dino oil breaks down into carbon sludge above 250 F!  Honda ran these engines at the oil's limit.

Get a can of SeaFoam, add 1-1/2 oz. per quart of oil, run it on the center stand for 5 minutes, shifting through all five gears while idling, to dissolve the sludge within the engine and transmission, then drain, and change the filter. Five minutes idling will warm the oil/engine to around 200 F, so no need for a fan, unless you want to.  You only need to add SeaFoam once every 15,000-20,000 miles, maybe longer.  Cheers!

[welovedon]

So can I just change my oil to the T6 by just doing a normal oil change?  Or do I have to flush it out and use Seafoam stuff??

[sgtslag]

The SeaFoam is not a flush, but a cleaner of sludge deposits.  SeaFoam treatment is purely optional, but recommended.


To switch to Rotella T6, just dump the old oil and filter, install a new filter, and fill with Rotella T6 oil.  No "flushing" required.  Cheers!

[welovedon]

great!  Thanks for all the help guys!