Topic: Oil Pressure ?

[Scootch]

What is considered normal oil pressure for the CB's? Let's say using 10-40. Cold start. After warmup.

[Jerry Rxman Griffin aka MuthaF'er]

CB750 cold oil 70 at rpm hot oil >10 at idle

[Scootch]

CB750 cold oil 70 at rpm hot oil >10 at idle

Awesome  thank you for responding  👍

[HondaMan]

10w40 oil is too light for a CB750, if that's what you are asking about.
Use never less than 15w40 diesel-rated oils, 20w50 is much better. Avoid detergent oils in the 750.

[Ellz10]

1-w40 oil is too light for a CB750, if that's what you are asking about.
Use never less than 15w40 diesel-rated oils, 20w50 is much better. Avoid detergent oils in the 750.

I saw this thread earlier and was waiting for your input, because we just had this conversation!   

[Tracksnblades1]

1-w40 oil is too light for a CB750, if that's what you are asking about.
Use never less than 15w40 diesel-rated oils, 20w50 is much better. Avoid detergent oils in the 750.

Sentence 2 & 3 are conflicting.  Use never less than “15w40 diesel-rated oils, …. Avoid detergent oils……🤔

Diesel oils are some of the highest detergent oils made, excepting perhaps Mobil 1…..
Detergent oils are known to neutralize acids and prevent oxidation and corrosions…

Even Shell’ AeroShell” non detergent 65 - 120 oil designed for piston engines (not non detergent hydraulic oil) is only recommended for break in for new or newly rebuilt. It’s been along time since the no oil filter engine days….

Even Honda originally included dg & dm (detergent diesel oils of the day) recommendations in their service manuals.

What non detergent oils of today are currently rated for flat tappet type camshafts or diesels  ?

🤔

[dave500]

compared to the 70s oils any decent diesel 15/40 or so is going to be way better than what was available in the day?only trouble truely is suddenly using a high detergent oil in a motor that has sat for years and dislodging perhaps a chunk that might obscure an oil passage?any motor thats been pulled down and clean will be fine with those oils,lets not start an oil thread right here?

[rotortiller]

 10w40 is fine for many of us. I have been using that weight for the last 10 years and have 80,000 klicks on the clock.  I also used the same weight back in the seventies. My bike does not burn any oil to date. It depends where you live and how you drive as to oil selection, just like with any other aircooled engine, base  oil weight decisions on operating conditions (CDF).

[Deltarider]

15W-40 is a good all round choice. I know Honda recommends 10W-40, but that's for all temperatures. You can ignore that: you will never operate your bike at such low temperatures. Your Honda would survive, but you wouldn't. The late racer Rob Bron advised me to chose the oil that cleans best and leaves no deposits. In his career he had tried several oils and had opened the engine of his racing bike numerous times. He condemned most oils and described them as oils with a powder added. His endverdict at the time: the cleanest oil, leaving nothing inside, was Esso Uniflo 10W-40, but... this is 50 years ago. I remember that oil. As a student I was a part time attendant at a gasstation and I must have sold tons of it. In Holland it was the first multigrade that could be used all year round. Before it was either 10W-30 for winters or 20W-40 for summers. Specific motorcycle oils were not around. -50 oils are to be used in very hot conditions only, like Arizona. In moderate climates like where I live, I see no use for it. As for pressure, I'd rather have an oil that circulates fast, than a thicker oil with more pressure. For my riding 20W-40 is probably best. On the other hand, I like the oil to arrive at the cam as soon as possible.

[Scootch]

I didn't mean to touch a nerve. I just changed the oil and put in Honda 10-40. I use 20-50 in Harley. I also just installed oil pressure gauge. Noticed that oil pressure on cold start is 60 psi. After warmup pressure drops. I'm in NY and temps in summer can be 50 or 60 mornings and 90+ afternoon.

[Deltarider]

Don't get me wrong: there's nothing wrong with 10W-40. In theory it arrives even faster at the cam during cold starts and that's where the wear takes place, not at the bottom. Do your bike a favour: avoid unnecessary cold starts (some estimate the wear is more than 300kms of riding) and avoid prolonged idling.

[Bodi]

I can find single grade non-detergent oil if I look super hard, it's not common. But I have never seen a non-detergent multigrade.
I bought a 1956 Dodge army truck from the government in around 1980 and after towing it home immediately did a good inspection - changed the belts, filters... and the oil using the typical multigrade oil of the day. It had apparently spent its 25 years with the Canadian army on non detergent oil. After that, I drove maybe 50 miles before the crank bearings spun. The drained oil was blacker - with those 50 miles on it - than I've ever seen drained oil be (except on utube) with many chunks of freed sludge and lots of sparkle. Expensive oil change. So if you get a "classic" that's likely lived on non-detergent oil be very careful about that or have the engine disassembled and cleaned internally before using modern oil. If there's another way to remove the sludge without risking blocked passages, I don't know it.
But... was non-detergent 10-30 oil common in the 70s?

[Scootch]

I don't know the history of this bike. I installed the oil pressure gauge two days ago and ran it for 100 mi to get a sense of what it was doing. I don't know what oil was in it but was advised to use Honda oil. Changed oil and filter yesterday. It was kinda black. Ran bike today and noticed oil pressure is 5 psi higher cold start and about 10 psi higher running and idling after warmup. Not sure if that is good or bad. If I hadn't installed a gauge I wouldn't know what the oil pressure is doing. Not sure what I'm into but it is what it is and time will tell...

[Deltarider]

Scooth, my experience is that with these bikes oil pressure is about the last thing to worry about. Personally I don't see what a pressure gauge brings, apart from a possibly hazardous distraction. Maybe this is why Honda made the choice not to fit one. I remember vaguely that in some maintenance scedules Honda wanted the dealer mechanics to check the oil pressure every 20.000 km or so. Nobody ever did, unless the customer specifically asked. Dealer workshops can perform such a pressure test for a few bucks. For the rest: don't let gadgets distract you. Eyes on the road at all times. The situation in front of you can change in a split second. Don't ask me how I know.

[Scootch]

Scooth, my experience is that with these bikes oil pressure is about the last thing to worry about. Personally I don't see what a pressure gauge brings, apart from a possibly hazardous distraction. Maybe this is why Honda made the choice not to fit one. I remember vaguely that in some maintenance scedules Honda wanted the dealer mechanics to check the oil pressure every 20.000 km or so. Nobody ever did, unless the customer specifically asked. Dealer workshops can perform such a pressure test for a few bucks. For the rest: don't let gadgets distract you. Eyes on the road at all times. The situation in front of you can change in a split second. Don't ask me how I know.

Thank you for the reminder. You make a good point. After I get a sense of what is happening I may remove the gauge 🙂

[ekpent]

Don't think you need to worry too much about what the oil is doing in there especially if you just did a 100 miler and all is good. Plenty of other fun stuff to worry about - 

[HondaMan]

1-w40 oil is too light for a CB750, if that's what you are asking about.
Use never less than 15w40 diesel-rated oils, 20w50 is much better. Avoid detergent oils in the 750.

Sentence 2 & 3 are conflicting.  Use never less than “15w40 diesel-rated oils, …. Avoid detergent oils……🤔

Diesel oils are some of the highest detergent oils made, excepting perhaps Mobil 1…..
Detergent oils are known to neutralize acids and prevent oxidation and corrosions…

Even Shell’ AeroShell” non detergent 65 - 120 oil designed for piston engines (not non detergent hydraulic oil) is only recommended for break in for new or newly rebuilt. It’s been along time since the no oil filter engine days….

Even Honda originally included dg & dm (detergent diesel oils of the day) recommendations in their service manuals.

What non detergent oils of today are currently rated for flat tappet type camshafts or diesels  ?

🤔

Shell's Rotella diesel is one good, low-detergent oil, and there are others. If you use high-detergent oils in diesel engines it can cause them to not be able to shut off, even when the Emergency Stop air dam has been dropped, if the engine is running hard and fast. The foaming oil becomes a fuel for the engine. We learned about that with 2400 HP frac engines in the 1980s when I was then directed to create halon-injection systems to guarantee E-stops when someone had installed the wrong oil by accident. It happened more than once! I can't even begin to describe how dangerous the situation was that this scenario created, but as it ended, I had 2 more 'backup' systems behond those to ensure shutdowns. That worked, and still works today.

[Don R]

 I think our difference is semantics of either low detergent or non detergent. My Dad used to seek out non detergent oil for his 46 farmall cub even after it was rebuilt and clean inside. Because it was what they had always used.
   I sold a flat of Valvoline non-D cheap to a guy for his old bulldozer when the collectors didn't want the cans.

[PeWe]

My both CB750 pressure at least 70PSI when idling when cold. 20W-50 oil.
I should never use thinner unless really cold outside.

Oil discussions are really interesting and good information for our bikes.

Oils changes constantly and adapts for cathalytic converters.
As low API class as possible is my thought to get higher amount of zinc and phosporous. Some oils have later API class but still very high amounts of zinc.
I think racing oils have more of it too.

Honda CB750 Users Manual recommend 10W-40 when ambient temp is max +15C, 20W-50 when warmer.

They might have similar recommendations for other bikes?

[Deltarider]

I should add that back then I was guided by a Dutch tribologist who has published several articles in both a motorcycle magazine as a mag for professionals in the automotive industry, also about oil pressure and oil flow. A higher oilpressure is not necessarily good. It's not the higher, the better. He owned a CB550K3 himself and preferred a 15W-40. He always recommended oils especially for motorcycles. What else could he do, as his articles were about motorcycles in general? From what I have learned, as far as my model, it's safe to deviate somewhat

[markmyodb]

Having just gone thru a rebuild of my 750 I  found problems with a new pressure switch, so I added a pressure gauge. It runs about 70psi when cold.  Drops to 15psi at idle once it is warmed up.

I use a 15-40 diesel oil because it has the JASO rating I was taught is important for wet clutches.  AND this oil is relatively inexpensive. AND I can put it in my Massey Ferguson tractor...

I have nice red Pensoil/Ferrari hat for stumping a barker at Road Atlanta with the question about why synthetic is bad for old Hondas.  My answer was its all hype, use it if you want as long as it has the JASO rating. His did not.

[TwoTired]

Oil is good.  No joy when in the teapot.  Source: Pete Townsend.

[Don R]

 While I was riding my Goldwing yesterday listening to the radio (thank goodness for the seek button) and checking the gauge panel that's nearly in my lap I remembered the oil pressure gauge comments. Just a bit of irony, maybe I can put a heads-up display in the windjammer.

[HondaMan]

While I was riding my Goldwing yesterday listening to the radio (thank goodness for the seek button) and checking the gauge panel that's nearly in my lap I remembered the oil pressure gauge comments. Just a bit of irony, maybe I can put a heads-up display in the windjammer.

Heck with the windshield! Put it in the helmet.
I use one of those half-shields with an overhead visor (like the one shown in my book's picture of me...in fact, I think it's the same one?)

[tourmax]

1-w40 oil is too light for a CB750, if that's what you are asking about.
Use never less than 15w40 diesel-rated oils, 20w50 is much better. Avoid detergent oils in the 750.

Sentence 2 & 3 are conflicting.  Use never less than “15w40 diesel-rated oils, …. Avoid detergent oils……🤔

Diesel oils are some of the highest detergent oils made, excepting perhaps Mobil 1…..
Detergent oils are known to neutralize acids and prevent oxidation and corrosions…

Even Shell’ AeroShell” non detergent 65 - 120 oil designed for piston engines (not non detergent hydraulic oil) is only recommended for break in for new or newly rebuilt. It’s been along time since the no oil filter engine days….

Even Honda originally included dg & dm (detergent diesel oils of the day) recommendations in their service manuals.

What non detergent oils of today are currently rated for flat tappet type camshafts or diesels  ?

🤔

Shell's Rotella diesel is one good, low-detergent oil, and there are others. If you use high-detergent oils in diesel engines it can cause them to not be able to shut off, even when the Emergency Stop air dam has been dropped, if the engine is running hard and fast. The foaming oil becomes a fuel for the engine. We learned about that with 2400 HP frac engines in the 1980s when I was then directed to create halon-injection systems to guarantee E-stops when someone had installed the wrong oil by accident. It happened more than once! I can't even begin to describe how dangerous the situation was that this scenario created, but as it ended, I had 2 more 'backup' systems behond those to ensure shutdowns. That worked, and still works today.

I don't understand why you would install a halon system to chop a diesel where a gate valve does a better job and you can buy them ready made for most intakes. Or, just slap a piece of plywood over the intake opening and it dies toute suite.

Not to mention, firing off a halon system requires hours of paperwork afterwards. We had halon fire suppression systems on all our choppers and fast movers and when one fired off accidentally (maintenance, not inhibited, tech not paying attention to which button/lever, etc) we would all let out a collective groan because we knew there was going to be hours and hours of environmental impact paperwork, investigations, interviews, etc.

I've never heard of a runaway diesel because it had a high detergent oil in the crankcase and I've worked on diesels for a good 35+ years. Sure, crankcase oil will burn in a diesel, but there's no way for it to get into the combustion chamber unless there a mechanical fault somewhere.

Not trying to bust your B's, but none of that makes any sense to me......