Topic: Oils well that ends well....but who knows if this will end well....

[Geeto67]

so while I am bored at work griping about my 73K for a minute. Let me ask a question....do you think Automotive oil is unhealthy for a SOHC4?

The reason I ask is that my oil light was flickering yesterday when I had the 73K warmed up to operating temp. A couple of times at a light I would get the red light of death, and reving it up would make it go away. Normally this is an indication of low oil level as pressure drops when the sump begins to pump air. So I get home park the bike no big deal. this morning (while admiring my newly formed gasoline lake - see my other post) I decide to check the oil. Seems pretty full to me and the color is right. no flecks either.

So I e-mail the PO and ask her what kind of oil she used to run in the bike. Admittedly I have owned this bike 6 months and broke my cardinal rule of giving the bike a good servicing since there were other issues that needed to be addressed (like the frozen front brake) and also since the PO told me she had just done an oil change. Anyway she tells me that she used to run regular automotive oil in the bike 10w-30 and I assume this means the cheapest she could find.

so here is my theory - regular water cooled cars run at a temp of about 160-210 for their warmed up operating range. Air cooled motorcycles run at about 230-260 degrees F for their warmed up operating range (based on the oil temp gauge on my aircooled ducati). My thinking is that this cheap automotive oil is actually getting to thin to hold decent pressure at idle when fully warm. Also I think the bike may be a bit low which is not helping, despite evidence to the contrary.

So here's your chance to tell me I am full of it.  Considering this is an oil thread, I anticipate many many pages....I'll make the popcorn.

[UnCrash]

I've got the butter and salt.

[Hope]

Are you really that bored at work?  If so, I will spice up the conversation and tell you which oil is really best for your 73.....


ready?


Here goes....

[Geeto67]

Just to be clear, I am not asking for an oil recomendation. I use Bel Ray or Spectro Synthetics in my SOHCs and have for years.

What I am asking is will conventional automotive Oil cause a low oil pressure condition when heated up or should I be looking at something else? Maybe the pump.

Gonna drop the oil pan and clean her out, she probably needs it.

[Joel]

I'm assuming your '73 is a 750.  The '72 owner's manual I looked in specified 10W-40 automotive service classification SE for general all temperature use.

The SE is an API (American Petroleum Institute) classification that is currently obsolete.  Any API SJ, SL or SM classification motor oil would meet the requirements for engine oil stated in the manual.

[scondon]

  I used to run conventional Castrol 10-40 and have since switched to Honda HP4 semi-synth. My bike burns a bit of oil over the 2000 mile service period so I buy an extra quart to top off with. It's been 2500 miles since my last change(man that went quick) and I ran out of HP4 so replenished with Castrol I had in the garage.

   HP4 (10w40) runs a solid 65lbs pressure when cold and 23lbs when hot no matter how old it gets.

   Since adding over a qt of Castrol to the mix it has dropped to 57lbs cold and 17lbs hot. I also used to get a warning light when revving low at stoplights with Castrol, usually before bike had reached full operating temps and not after. I don't get this with HP4.

[TwoTired]

If you are thinking it has 10-30W in it, it's too thin unless you are riding exclusively in temps below 60 F.

If you're engine is out of tune and running hotter than it would if the timing were correct and the carbs weren't lean.  Then that is certainly too low an oil viscosity.

You also don't know if you do have oil pressure issues.  At what pressure does your light come on?  Your oil press sender is perfect?

No, I don't think automotive oil is particularly bad for the SOHC4 engine (when new and if it doesn't contain Moly).  However, modern auto oil doesn't last as long as oil intended for transmission gear lubrication use.  The long chain molecules in the additives that make it behave as multi vis oil, get chopped up and then it loses its ability to behave as a higher viscosity oil.  Old, used, abused oil behaves as its lowest viscosity index.  If it started out as 10-30W oil, it turns into 10W oil (or whatever the base stock oil is) in a MC transmission.  And, according to Honda, such an oil would only be suitable in temps below 32F.

While not an oil pressure issue, modern Auto oils have also taken out the zinc and other metal additives that poison catalytic converters, but are beneficial to lubing trans gears.  That's how I understand i, anyway.

Lastly, if your carbs are over flowing, can you be certain that your oil isn't contaminated with gas?  That would sure lower the viscosity by dilution, if not help the oil additives break down, permanently losing some multi-vis behavior.

Cheers,

[Joel]

  I used to run conventional Castrol 10-40 and have since switched to Honda HP4 semi-synth. My bike burns a bit of oil over the 2000 mile service period so I buy an extra quart to top off with. It's been 2500 miles since my last change(man that went quick) and I ran out of HP4 so replenished with Castrol I had in the garage.

   HP4 (10w40) runs a solid 65lbs pressure when cold and 23lbs when hot no matter how old it gets.

   Since adding over a qt of Castrol to the mix it has dropped to 57lbs cold and 17lbs hot. I also used to get a warning light when revving low at stoplights with Castrol, usually before bike had reached full operating temps and not after. I don't get this with HP4.

That would seem to support the general conclusion that motorcycle-specific formulations are better however some of that effect could be due to the semi-synthetic properties of the HP4.  Maybe automotive synthetics would provide the same results.

[silentone]

Here's a nice lengthy article on the subject: http://www.xs11.com/stories/mcnoil94.htm

For those who don't want to read it all... the summary states:

"MCN cannot and does not purport to know all there is to know about the differences between automotive and motorcycle oils. However, what we do know is that we can find no substantive evidence that using a high-quality, name-brand automotive oil in an average street motorcycle is in any way harmful or less effective in providing proper lubrication and protection than using the more expensive, motorcycle-specific oils."

[TwoTired]

  I used to run conventional Castrol 10-40 and have since switched to Honda HP4 semi-synth. My bike burns a bit of oil over the 2000 mile service period so I buy an extra quart to top off with.

I forget where, but I remember reading that Honda's HP4 has a high evaporation rate.  This is likely your loss issue rather than an actual burn.  Unless, of course, you are showing oil deposits on the spark plug electrodes.

The article was about a newer Honda with a much longer oil change interval.  He basically ran out of oil, because of evaporation, didn't check it between oil changes and was pissed at Honda because the engine fried due to lack of oil.  Some synthetics evaporate at a lower temp than others.

Cheers,

[jsaab2748]

Lastly, if your carbs are over flowing, can you be certain that your oil isn't contaminated with gas?  That would sure lower the viscosity by dilution, if not help the oil additives break down, permanently losing some multi-vis behavior.

Cheers,


Along with T.T.'s techniclal explanation, his last paragraph is good advice. I've seen this happen in cars that had defective mechanical fuel pumps that allowed fuel to get into the oil. Can thin the oil out a lot.

[/quote]

[Geeto67]

it was doing it before the carbs started leaking. Anyway, I am home from work now - time to walk the dog then hit the garage

[bryanj]

Is automotive oil OK, Dunno, but I been using Silkolene(Fuchs) Transfleet 10W40 fleet diesel oil for years and had no problem

[Joel]

... However, modern auto oil doesn't last as long as oil intended for transmission gear lubrication use.  The long chain molecules in the additives that make it behave as multi vis oil, get chopped up and then it loses its ability to behave as a higher viscosity oil.  Old, used, abused oil behaves as its lowest viscosity index.  If it started out as 10-30W oil, it turns into 10W oil (or whatever the base stock oil is) in a MC transmission.  And, according to Honda, such an oil would only be suitable in temps below 32F...

That's a great point I hadn't thought of.  I'm sure most automotive oils aren't designed with transmission and clutch lubrication in mind and thus may not be as well suited as one that is.

[City Boy]

Anyone interested in oil 101 should read the complete article referred to by Silentone.Assuming the scientist is being truthfull,his findings dispel any rumours/old wives tales vis a vis car/bike oils.The one thing I do wish he had done was use an air cooled motorbike rather than watercooled.To reiterate a post of mine on another oil thread,I use Rotella T 15w40 in my units and I have a pal who uses WalMart Tech 2000 20w50 at $8/galoon in his daily driver 750.$8 is the cheapest oil I have seen anywhere.Both of us are very satisfied with our choices.Having said that,you should use whatever makes you feel good,no price can be put on peace of mind.  Rock On

[Dave Wyatt]

Yippee, an Oil thread!!!

I don't pay attention to reccomended weights of oil in any vehicle.  They suggest the lightest crap to meet various requirements, and sell more vehicles.  I'm old school and like heavier oil.  I run 20W50 (Castrol or Valvoline) in the Hondamatic, and it will idle way down and never does the light flicker.  That is with a 3000 mile oil change schedule.  In my truck and car, I use Mobil1 synthetic of the 5w30 variety and change it at 5000 miles.  If I can figure out a good way to empty the torque converter, short of dissasembly, I'll switch it to Mobil1 10W50 someday, but stay with 3000 mile intervals. 

In my 70 4-4-2, I got away from regular 20W50 Castrol or Valvoline, and went to 20W50 Valvoline racing oil, since it's a tad heavier out of the bottle.  My son picked up oil pressure in his 455 Olds when he changed to the Valvoline Racing 20W50, so I figured it wouldn't hurt the 4-4-2.  I may go to that in the Honda, instead of switching it to synthetic.

[Geeto67]

I run 10w50 or 20w50 in my GTO but that is because pontiacs are notorous for running hot (190-210 is normal the temp light doesnt come on until 240-260).

Thanks for the help guys. I think the key here was the PO was throwing in whatever she could find at gas stations, not even a quality motor-oil. An oil change is in store this weekend.

[754]

Some people,
take oil is oil,
a wee bit far.
when they pull
up on a CB 750
and say, 2 stroke
oil should be OK?
I just shake my head.

[TwoTired]

I don't pay attention to reccomended weights of oil in any vehicle.  They suggest the lightest crap to meet various requirements, and sell more vehicles.  I'm old school and like heavier oil.  I run 20W50 (Castrol or Valvoline) in the Hondamatic, and it will idle way down and never does the light flicker.  That is with a 3000 mile oil change schedule. 

The purpose of the lower weight is to minimize wear when the engine is cold.  Thick oil is great for when the engine is good and hot, but, very sluggish at start up  The very high oil pressures you see at startup correspond with very low flow rate of thick oil.
It makes a big difference what temp the bike is at start up.  In summer, when the engine starts out at 70 F, 20W still provides flow and lubrication.  But, move that start up temp to 40 F, and the oil circulation suffers, and the chance to not get enough lubrication to parts not yet at operating temperature.  Certainly, flow and pressure also have a relation to the clearances your engine has.  A new engine with tight tolerances needs a thinner oil than one that has either been designed to have larger tolerances or one that has seen plenty of operational wear.  The manufacturer recommendations for oil weight coincide with the factory tolerances built into the engine to give the best flow and pressure over the defined operating conditions it has outlined.
Many people think that metal material is quite dimensionally stable.  But, the parts all change size and relative fit, in relation to temperature.  These parts wear in for best fit at operating temperature.  Going outside of that operating temperature too cold or too hot, generally means more wear of certain parts during that abnormal parts fit.

The trade off with oil viscosity relates to how you operate your bike.  Lots of cold starts in relation running at full operating temp favors a thinner weight oil.  Few starts and lots of time running at full or high operating temp favors a thicker oil.

Cheers,

[scondon]

I don't pay attention to reccomended weights of oil in any vehicle.  They suggest the lightest crap to meet various requirements, and sell more vehicles.  I'm old school and like heavier oil.  I run 20W50 (Castrol or Valvoline) in the Hondamatic, and it will idle way down and never does the light flicker.  That is with a 3000 mile oil change schedule. 

The purpose of the lower weight is to minimize wear when the engine is cold.  Thick oil is great for when the engine is good and hot, but, very sluggish at start up  The very high oil pressures you see at startup correspond with very low flow rate of thick oil.
It makes a big difference what temp the bike is at start up.  In summer, when the engine starts out at 70 F, 20W still provides flow and lubrication.  But, move that start up temp to 40 F, and the oil circulation suffers, and the chance to not get enough lubrication to parts not yet at operating temperature.  Certainly, flow and pressure also have a relation to the clearances your engine has.  A new engine with tight tolerances needs a thinner oil than one that has either been designed to have larger tolerances or one that has seen plenty of operational wear.  The manufacturer recommendations for oil weight coincide with the factory tolerances built into the engine to give the best flow and pressure over the defined operating conditions it has outlined.
Many people think that metal material is quite dimensionally stable.  But, the parts all change size and relative fit, in relation to temperature.  These parts wear in for best fit at operating temperature.  Going outside of that operating temperature too cold or too hot, generally means more wear of certain parts during that abnormal parts fit.

The trade off with oil viscosity relates to how you operate your bike.  Lots of cold starts in relation running at full operating temp favors a thinner weight oil.  Few starts and lots of time running at full or high operating temp favors a thicker oil.

Cheers,

Well said

[Dave Wyatt]

And that's why I like the 20W50.  It flows well enough on cold starts, but doesn't turn to water when the temps go up.  If it gets below 40f out, I rarely ride.  And if it gets into the 20's, the Honda stays in the garage.  So cold starts, in actual cold weather, are pretty rare.  I'll still stick with the heavier oil to keep it alive the rest of the time.

[mustangcar]

from what iv been told,and from what the what the famous Competition cams (brand)maker recommends is Rottella oil i use 15w40,, diesel oil,has a higher zinc level ,,,zinc has been eliminated from auto oils because it plugs up catalytic convertors,heard zinc is a biggie for lubrication,,great for motorcycles with wet clutches,i use the non synthetic,to each is own im stuck on Rottella