'87 K75 Oil Leak Caused by Spectro Oil?

[st3ryder]

Well, after a 8000+ mile tour, I found a small pool of oil under my bike, just behind the centre stand. Bike had not run for 6 days. I immediately thought it might be the rear engine seal, (approx 60K, 21 years old) but upon a closer inspection, now feel it's seepage coming through the rear of the oil pan gasket. I used Spectro Golden 10W40 100% synthetic for my last oil change as I was on the road, and had little choice. I remember years ago, using full synthetic was frowned upon due to oil leaks in older engines, but then they changed the base stock, and all was well. I'm wondering if Spectro might still be using the old type esters/base stocks, and caused the seepage? Of course, I'm not ruling out the rear seal, but the oil "wettness" pattern at the bottom of the engine lead foreward/"upwards" from the hole in the bell housing, ie rear end of the gear box-engine was lower than front end. An oil leak from the rear seal, coming out the bell housing hole wouldn't run uphill, would it?

[PGlaves]

Well, after a 8000+ mile tour, I found a small pool of oil under my bike, just behind the centre stand. Bike had not run for 6 days. I immediately thought it might be the rear engine seal, (approx 60K, 21 years old) but upon a closer inspection, now feel it's seepage coming through the rear of the oil pan gasket. I used Spectro Golden 10W40 100% synthetic for my last oil change as I was on the road, and had little choice. I remember years ago, using full synthetic was frowned upon due to oil leaks in older engines, but then they changed the base stock, and all was well. I'm wondering if Spectro might still be using the old type esters/base stocks, and caused the seepage? Of course, I'm not ruling out the rear seal, but the oil "wettness" pattern at the bottom of the engine lead foreward/"upwards" from the hole in the bell housing, ie rear end of the gear box-engine was lower than front end. An oil leak from the rear seal, coming out the bell housing hole wouldn't run uphill, would it?

I'm more concerned by your statement you used 10w40 wt - which is speci'd only up to ambient temmperatures not over 68 degrees.

[bmwmick]

I agree,
10W40 is too thin if the temps are above 70 degrees. As for synthetic causing leaks, No, it won't but if you already have a leak, it may get worse. The "synthetic causes leaks" was valid for about 6 months, WAY back in 1974 or so.

[Gilly]

just FYI the Golden Spectro is a semi-synthetic not a full synthetic. I used it exclusively in the 87 S I sold this summer, but I used 20W50. Only leak i ever had (in 95000 miles) was at the pump seal, I think it was a coolant leak though, can't remember now.
The oil BMW sells (or at least sold back in the day) was Golden Spectro.
My dealler said they still use it in my new GT, although the manual wants me to use Castrol GPS. Hard to believe BMW wouldn't stand behind the warranty if I use BMW oil. Just the same when I do my own oil change I'll probably look for the GPS.
Gilly

[st3ryder]

Ooops, my bad, it is 15w50, not 10W40, and it was their "Platinum" brand, not Golden, ie 100% syn. In any case, it is not weeping gaskets, nor a rear engine seal, but I traced the "leak" to the crankcase breather hose. I'm guessing all the high speed riding I was doing on those nice US interstates, ie crusing 85mph for hours, and the fact that I topped it all the way up with a full 4 litres, caused some to get blown out the crankcase breather hose that I taped-up before leaving since it had a few cracks in it, and drip down the cases to eventually drip off at the hole in the bell housing leading me to think it may be a real seal, or weeping oil pan gasket. All is well, except I need a new crank case breather hose. :)

[osbornk]

I agree,
As for synthetic causing leaks, No, it won't but if you already have a leak, it may get worse. The "synthetic causes leaks" was valid for about 6 months, WAY back in 1974 or so.

I don't think you are right. I had a 85 K100RT that was dry with Dino oil. I changed to Mobil 1 and the rear seal started seeping enough to leave a drip on the floor. I changed back tgo Dino oil and the seepage stopped and the bike again was dry.

I bought a R80RT that I found that was sitting on a dry carpet in the owner's garage. He had just changed the oil to synthetic. I bought it and rode it for a few days and the tube seals began to seep oil that dripped on the rug. I changed the oil to Dino and it quit leaking. I have kept Dino oil in the airhead for the last 10 years and it is still dry.

If I had the leaking problem once, I might have blamed it on the bike but since it happened to me twice on two totally different bikes, I will not make the mistake of using synthetic in an older engine again.

[breyfogle]

.... I topped it all the way up with a full 4 litres, caused some to get blown out the crankcase breather hose ....

On my K75, no matter how much over the sight glass center dot I fill the engine, it will very quickly pump itself down to the center dot level. Doesn't matter if it is just a but over or "filled to the max". Doesn't matter if I'm touring or commuting. Once the oil level gets to the center dot level, it will stay there until the next oil change.

When the bike was new, it scared the s* out of me on the first couple of long trips. I would change the oil and top it off before the trip (old habit from airhead days). By the end of the first day out, the oil level would be down to the center dot level. Loosing that much oil in one day on the road was not something I was used to. Once I figured out that the oil level would stay at the center dot level for the rest of the trip, I stopped worrying about it.

In my experience, putting any more oil in a K75 than the 3 and 3/4 quarts or so it takes to reach the center dot, is just a waste of good oil.

[deilenberger]

On my K75, no matter how much over the sight glass center dot I fill the engine, it will very quickly pump itself down to the center dot level.
Snippage..
In my experience, putting any more oil in a K75 than the 3 and 3/4 quarts or so it takes to reach the center dot, is just a waste of good oil.
Contrary to that experience - neither my '85 K100RT or my '87 K75S ever exhibited that behavior. I always filled to the top of the window, and it was still filled to the top of the window 6,000 miles later when I changed the oil.

If you think of the design - where the sump is well below the crankshaft - I can't see why the difference of 1/2" in oil level should make a difference. Dunno what's up with your bike, but that wasn't my experience with mine.

Oh - used Castrol dino oil (RX-Super fleet oil) on the K100, Mobil-1 on the K75. Neither leaked.

YMMV (and apparently it does..)

BTW - I also run my Hexhead at the top of the window, where it's been for the past 4,000 miles, hasn't dropped a MM so far..

[Gilly]

On my 87 I could use the site glass as an oil change indicator. It would be at the top after a change, hang around the dot most of the life of the oil, and around 4000 or so, about when I'd change it, it would be near the bottom of the site glass.
Gilly

[bicyclist]

On my K75, no matter how much over the sight glass center dot I fill the engine, it will very quickly pump itself down to the center dot level. Doesn't matter if it is just a but over or "filled to the max". Doesn't matter if I'm touring or commuting. Once the oil level gets to the center dot level, it will stay there until the next oil change.

When the bike was new, it scared the s* out of me on the first couple of long trips. I would change the oil and top it off before the trip (old habit from airhead days). By the end of the first day out, the oil level would be down to the center dot level. Loosing that much oil in one day on the road was not something I was used to. Once I figured out that the oil level would stay at the center dot level for the rest of the trip, I stopped worrying about it.

In my experience, putting any more oil in a K75 than the 3 and 3/4 quarts or so it takes to reach the center dot, is just a waste of good oil.

Both of my K75s do the same thing. They like the oil level at the red dot.

[Kayseventyfive]

There strong opinions on both sides of the synthetic oil leak discussion, many the result of experience.

I have had Mobil 1 cause a leak on some vehicles and not on others.

On a Chev LT1, the leak was so bad I had to replace the rear main seal. Examination showed that the adhesive holding the rubber lip part to the metal shell had failed for about half of its circumference. This was the original OEM seal, but was a brand I had never heard of. Not CR or another familiar brand.

[breyfogle]

- I can't see why the difference of 1/2" in oil level should make a difference.

I have no idea either but the "feature" has remained consistent as the bike accumulated miles and as its usage changed from sport-touring to urban assault vehicle.

BTW - I also run my Hexhead at the top of the window, where it's been for the past 4,000 miles, hasn't dropped a MM so far..

My R1100 (at 48K miles) is the same way. It uses absolutely Zero oil between changes. Fill it to anywhere visible in the sight glass, forget about it, repeat 5000 miles later.

[st3ryder]

My '87 K 75 doesn't use enough oil in between changes to warrant adding a drop, no matter what type of oil I use. The only other MC I've owned that compares to that is my Ducati. The oil level does not drop in the sight glass. I use dino, Rotella, for storage just to have oil in the engine, and syn 5-20W50 for running, always automotive type oils, ie not MC specific: Never any oil leaks from seals or gaskets. (so far anyways) The reason I posed the question is because I selected a MC specific full syn oil due to lack of choice last oil change, and had not yet traced the leak to the breather hose. It did appear to be seeping out of the oil pan gasket, and this evoked memories of early full syn issues, prompting me to wonder if the Spectro was causing gasket seepage/weepage like full syntehtics were accused of doing way back when.