The need for an oil cooler for street riding? (GS1000G)

[Guest]

As my signature indicates, I have two GS1000G models. I have fitted oil temperature gauges to both. The gauges are the same brand. I never do any 2-up riding and my maximum road speed is 70 MPH on the Interstate. Being in a rural area, I seldom do any city riding with extended idling.

On my red '81, I added an oil thermostat that is supposed to open at 180 degrees and flow oil to the cooler, which is a small tube & fin model under the fairing. I did a write up on it if you want to search for it. The engine has an oil cooler adapter on it and flows oil to the t-stat. In the outgoing AN-6 line, I have fittings to monitor oil pressure and temperature. I noted lots of oil pressure when cold, often hitting 40 PSI on the gauge. I still see about 15 at road RPM when it is hot. Oil temps rarely rise above 140, and on the road in 90 degree weather are usually around 130.

On the blue '80, I mounted a tee for oil temperature and pressure using the galley plug on the right rear of the engine.

This past weekend, I had the opportunity to ride in 102-111 degree ambient weather in Georgia on the blue bike. I saw warmer temps, but it maxed out at 170 in town at lower speeds. Even in sustained 102 degree heat, it stayed around 150 degrees.

I have confirmed the temps by using a laser thermometer on the fittings where the sensors are located.

To contrast this, I have a 25 HP Kohler engine on my lawn tractor and fitted a mechanical gauge to it when I replaced the original 20 HP B&S engine. I also added an oil cooler that was a small tube & fin power steering cooler, and a thermostatic oil cooler/filter adapter. It sits over the fan intake for airflow. When the deck is engaged on a 90+ degree day here in Florida, I'll see temps of 220. If I'm not mowing, it drops to about 190. This engine had an optional oil cooler, so I knocked off the design using used parts.

This has led me to believe I do not need the cooler on the red bike due to the design, the extra air flow available while riding, and my riding habits.

[Dogma]

I doubt you need an oil cooler unless you're hammering the throttle in a sporty fashion, or have a lot of mountains to climb. I don't have a cooler on my 1000G, and I only notice high temperature symptoms when I'm somewhere in the Appalachians. I don't have an oil temp gage mounted, but it feels hotter, it once smelled hotter, and the ticking noise nobody's figured out yet gets worse.

Since you have the instrumentation, would you be willing to block off the cooler and see what happens? I'm thinking tolerable operating temperature is much higher than what you're reading, well over 212°F

[GS1000G Shopper]

I could either make a plate or loop the output hose on the thermostat, but seeing as how the oil never gets up to 180 degrees to fully open it, I doubt there would be a difference. If I go to wrench on it, it will be to pull everything and relocate the senders.

The blue bike serves as an example of a bike w/o a cooler.

I used a sheet metal block off plate for my former C10 Concours when I had an oil temp gauge on it. Despite being liquid-cooled, as I recall it never got above 150 or so in the summer, and was usually around 120. The plate did not make a difference on it, and I was going to plumb in a thermostat before I sold it.

[Nessism]

Your temps seem too low. My 1000S has a temp gauge which I calibrated it by checking with boiling water, and my oil is routinely running into the mid-upper 200's during hot days. I've been thinking about adding an oil cooler w/thermostat, only I don't think it's strictly necessary.

[tom203]

Your temps seem too low. My 1000S has a temp gauge, and I calibrated it by checking with boiling water, and my oil is routinely running into the mid-upper 200's during hot days. I've been thinking about adding an oil cooler w/thermostat, only it's hard to justify.

Yes, I've measured my oil temp a few times after 2 hour ride in 80 degrees and got 220 + using instant read thermometer probe which has been checked against boiling water.

[Flyboy]

This has led me to believe I do not need the cooler on the red bike due to the design, the extra air flow available while riding, and my riding habits.

You believe correct, no need for an oil cooler on the 1000G.
Jennifer has never had one, and I have spent years in stop go traffic on 30C days as well as extended highway cruising, and never experienced any cooling problems.
I agree with Ed, if anything, your oil temps seem on the low side.
Oil usually runs at 200F+

[jeff.saunders]

I'm not a fan of oil coolers unless they are absolutely needed.

There are some inherent problems with oil coolers.

If you ride on a very cool day, even those coolers with a thermostatic bypass can overcool the oil so it doesn't come up to full temperature. In some cases you have to cover the cooler to eliminate the cooling. If you start seeing milky white oil in the level window, it's a sign the engine isn't getting hot enough to burn off condensation.

If the cooler is mounted with the fittings on the underside of the cooler, the oil will gradually drain out of the hoses and cooler. When you fire the bike up after it's been sitting for a while, the first 10-15 seconds of running, you have no oil pressure to the top-end of the engine.

Oil coolers also reduce the effective oil pressure to the engine - the oil has to be pumped to the cooler and back to the engine - not a big deal, but you are reducing the oil pressure slightly.

[hjfisk]

Not sure how accurate it is but my 83 750 has an oil temp gage and I have seen it at 240 many times , and it has a factory cooler, small but still a cooler. Also seen it get up over 300degrees once when I was younger and decided to fill up with Cam2 race fuel 112 octane on a 100 degree summer day. Not one of my proudest moments.

[Nessism]

Not sure how accurate it is but my 83 750 has an oil temp gage and I have seen it at 240 many times , and it has a factory cooler, small but still a cooler. Also seen it get up over 300degrees once when I was younger and decided to fill up with Cam2 race fuel 112 octane on a 100 degree summer day. Not one of my proudest moments.

I'm pretty sure high octane fuel doesn't burn any hotter than regular fuel. I believe the high oil temp you experienced was due to the hot weather.

[Nessism]

Oh, and regarding the oil pressures, you are getting way more pressure than I've experienced as well.

My 850 had an oil pressure gauge and only when cold would the pressure get up in the high single digit range. When hot the oil pressure was so low it was scary - low (very low) single digit range. I can't imagine 15 psi when hot with one of the roller crank engines.

[Retard]

http://www.theflyingbanana.com/oil-cooler.htm

[GS1000G Shopper]

I see I missed a lot of replies here.

The temps seemed way low to me as well. I used the best means I had at hand- a laser thermometer- and measured the brass fitting where the temp sender is located. It was within 5 degrees of the gauge temp after riding.

My blue bike has a cylinder head temp (CHT) gauge. I don't have the correct sender for it (thought they worked the same under the spark plug so I got another less costly brand), so it reads about 75-100 degrees too high according to my laser thermometer- in the area of 400-425 degrees at 60 MPH on a 90+ degree day here in Florida. From what I've read, CHT on aircraft is usually in the 300-350 degree range, so the GS is pretty much in line with those.

I have a mechanical oil temp gauge on my 25 HP Kohler twin cylinder vertical shaft lawn tractor. I've added a thermostatic oil filter adapter and a cooler that is a simple power steering cooler from a 60's Chevy. The cooler is mounted on top of the fan area so as to draw air though it- similar to the location of the optional factory Kohler cooler. Under load (mowing) on a hot (95 degree) day, I saw temps of 245 degrees recently. It of course does not have the advantage of lots of air at 60 MPH and all of the exposed surface area to dissipate the heat.

I'm likely going to pull the cooler setup off the red bike soon, and will try to check the calibration of the gauge in a pan of water with a kitchen thermometer.

Thanks for all of the input.

[tkent02]

I never heard of a properly running eight valve GS engine having problems due to hot oil, in deserts, stop and go city riding, mountains, anywhere. I have an oil cooler on my 1100G, seems a waste but the PO put it on, I haven't bothered to remove it. I will before this winter. It doesn't run any differently, the oil doesn't last any longer than any of the other GSes. Oil that never gets up to a proper operating temperature is not a good thing. Also a cooler is a leak waiting to happen, it can't leak if it's not installed.

In your case, with moderate speed cruising and a well maintained engine, I wouldn't even think about adding a cooler. If you are the slightest bit concerned about your oil temp, use synthetic oil and forget about it.

The later sixteen valve engines with little air flow through the head, it may be a different story, but mine have always run fine as is.

[1_v8_merc]

Often times, a cooler is added to compensate for a badly maintained bike!
(bike sputters in the heat, they assume it's overheating)

A similar situation, is how many new riders immediately replace their coils, the moment they have issues with Idling or Starting. 90% of the time, it's dirty fouled connections, bad charging system or carburetors that were Not cleaned and rebuilt properly.

[salty_monk]

The 83GS750 has a more evolved system than any aftermarket one.
There is a thermostatic non return valve incorporated in the oil pan and the engine works on a much higher oil Pressure.

My prior 1000G and 1000E have both been in temps over 110 degrees. On G I used to experience slightly elevated idle speeds when stuck on Wiltshire Blvd in 100+ heat but with the E I don't even get that.
Put the difference down to The carbs and the slightly less oil volume in the G.