2 oil questions DOHC 750cc

[LukeM]

I believe it's been asked before, but I'll walk it out there once more.
1.  On the front of my DOHC 750, there is a line that kind of circles the oil filter cap.  I would assume this is part of the oil path.  Could this line be used to splice in an oil cooler?  Is there some provision for adding an oil cooler to the 750cc DOHC engine?  (I know there is one on the 900cc engine.)

2.  On some older car engines, oil companies recommend a high mileage oil that supposedly helps valve guides and seals to tighten up, thereby lessening oil burning past these components.  Can the DOHC engine run with this kind of oil, assuming one stays with the 10W40 recommended?  Will anything in the clutch or transmission go *prang* if this kind of oil is used?

Thanks in advance for your input.
Luke M

[vern401]

I have noticed that these older bikes temd to become picky with the oil. My cx will not shift right on Penzoil but loved castrol. the 750 I havent run enough to know, the sl350 i can use almost anything. So I would say it depends on the bike. Normaly I just use Castrol GTX in the bikes.
As far as the cooler I have no idea. Sorry

[Re-run]

Well Luke, I can't say anything about #1 without being able to see a pic of it. But I would doubt honda added this extra line for an oil path. I suppose it is possible but I suspect it might have been added by a previous owner.

As for oil, 2 rules generally apply. 1: the oil be at least the recommended weight, especially the second number. 2: That it is not an "energy conserving" oil.

Almost all oil has moly in it, even oil sold by honda as their own that is for use in wet clutches.
The problem comes when there is too much of it.

In my 78K, I used to valvoline 10-40. It was ok, nothing bad. Switched to rotella T which is a 15-40 oil. A little thick but shifts few nice. Then switched to the rotella synthetic and WOW. That tranny shifted great and the engine ran so smooth! No burning oil and contrary to erroneous old school thought, no leaking on seals. Synthetic oils these days are vastly superior to conventional oil. If you develop a leak at a seal now or in rings or valves, it is because they were already worn out to begin with, your old oil sludged up and formed a sort of temporary seal. That is one of the beauties of synthetic, keeping your engine clean.

The rotella oil is a diesel oil so it has more zinc in it which can be beneficial for motorcycles.
The synth is most costly, yes, but I can go longer between changes too so the cost is not so great.
If anything, maybe try the rotella T which is comparable in cost to other conventional oils.

[woodsrider250]

This is the coolest/easiest way to attach an oil cooler that I've seen without swapping in 900 parts.  Look at bottom:

http://www.randakks.com/Engine%20Parts.htm

+100 on the Rotella-T Synth

[LukeM]

I finally got a pic of that oil pipe on the front of my engine.  I had to pull the crash bars to get the oil filter changed.  So, it looks like this is just a loop of hose from the input side of the oil filter to the output side.  What do you think?

Luke M

[Re-run]

Definitely an oil cooler there. Just missing the cooler.

[LukeM]

I'll have to think about getting one and where to mount it. I'll worry about this after I get the bike running again.  Can't just keep throwing money at this thing...can I?

Luke M

[Re-run]

A small radiator should work pretty good. I think you will just need to fab a bracket to mount it to the frame.

[LukeM]

That IS an aftermarket adaptor.  I took it off when splitting the cases on my bike.  The plate bolts in place where the filter goes home.  I may take it off, since it's just holding a bit more oil than normal, and not really cooling it any.  I think I can put it back on without any bigtime drama.

The moto mechanic also recommends the Rotella diesel oil.  He was a mechanic for a trucking company for 20+ years, and says Rotella regular and synthetic are some amazing oils.  Well worth the price.  Looks like I'll be using that as well, after the motor is broken in.

Luke M

[sgtslag]

I put an oil cooler on my '79 CB750K, with an oil thermostat.  Without the cooler running, riding two-up, with luggage, on a tour, my oil ran 250 F!  With the cooler running, the oil dropped to 190-210 F!  The air temperature that day was mid-80's...

Dino oil breaks down at 250F and above.  The cooler you maintain your engine's oil, the slower it will break down.  If you run synthetic, no cooler is needed, except to save seals from excessive heat, which breaks them down faster (synthetic oil breaks down at 400 F+).  If you do install a cooler, I would highly recommend you install an oil thermostat:  bypasses the cooler until the oil reaches 180 F; automatically bypasses the cooler when the temperature drops below 180 F.

You should also install an oil temperature gauge with a cooler.  When the air temperature drops below 60 F, you may need to cover the radiator.  With some brands of oil thermostats, 10% of the oil will flow to the radiator even when the oil is cold.  This prevents thermal shock, pressure loss (opening/closing of the valve), and foaming (oil rushing into an air filled hose/chamber).  The temperature gauge also helps you monitor the cooling system's function.

If you decide to tackle the oil cooler project, let me know.  I can share with you my experience, and the design I followed to install it.  My cooling system has 1,500 miles on it, and it works perfectly, until the temperature drops below 60 F, when I need to cover the radiator so the oil can reach 180 F (thermostat...).  Cheers!