All sortsa' oils

[lukasgrech]

Couple of oil questions (for my '79 R65):

1. My engine oil level is coming close to the MIN level, so it's time for a fill up, however as this is my first oil refill on this bike, I don't know what oil the PO used. -- Should I drain the entire sump and refill with completely fresh oil?

2. Which oil grade should I use? (My first oil change, I do beg your pardon for my ignorance).

Manuals and their suggestions don't quite line up with what's on the market. Will a 10W30 oil do? Do oils with 'Racing' in their name qualify for use?

3. Discovered a small pool of golden coloured oil under the bike (been standing for 3 days). Oil is dripping from the nut at the bottom of the gearbox (you can kindof make out a drop forming on the nut in the photo). The location makes me think it's gearbox oil, but the look and touch of it seems more like engine oil - although no signs of leakage from the sump drain plug.

[Ed Miller]

The owner's manual (one on this site, somewhere) shows the right oil viscosities to use for different temperature ranges.  I don't know which is right for you, probably 10W-40 or 20W-50.  Ignore the term "racing."  

How long/how many miles since the oil was last changed?  It's probably time for that, and you will probably want to change the filter as well.  Look for posts on this site on the filter/shim/O-ring, as it's a little complicated.  It may be time to change the oils in the tranny, drive shaft, and final drive, too.  

That oil in the picture is probably not coming from the gearbox cover, but you will have to clean things up under there pretty dry to be able to tell where it is coming from.  It seems like oil blows all over under there if there is a leak.  

[Barry]

You should be able to tell if the oil is from the gearbox or engine by the difference in smell with gear oil usually having a distinctive odour.  Likely culprit is the neutral switch visible in your pic.

Whether you top up or change the oil don't fill above half way between min and max marks on the dipstick. This is to maintain some air space in the sump which will minimise oil loss via the engine breather. This is a generally accepted policy across all airheads and is particularly applicable to a 79 as it has a slightly shallow sump than the later models.

If you are going to top up I wouldn't worry too much about what to put in. What oil have you got to hand if any ? I'm a fan of 10w40 but 10w 30 is definitely too thin for year round use even in our climate.

The oil chart in the riders handbook gives BMW's view in 1979 which is still going to be fine as far as protecting the engine. They did however  through a series of service bulletins provide revised guidance over the years as oil specifications changed. Generally there was a move to accept the use of thinner oils like 10W40 at higher ambient temperatures. This chart issued in 1995 is the latest one definitely applicable to airheads.

[lukasgrech]

Thanks for the replies and the pointers.

I don't have any oil to hand at the moment.

The leaked oil doesn't have any distinctive smell.

Looking for more than a few minutes, the leak is quite clearly coming from the swingarm to gearbox rubber boot.



The boot is horrendously swollen in two spots, almost certainly porous there and the zip-tie has come off.

From what I know about the replacement procedure for this, this is not a one man, standard-tools job. Any advice?

[montmil]

It does not get terribly cold in Texas so I maintain my three Airheads with Castrol 20W50 engine oil that meets the BMW's need for an SJ / MA2 spec oil. Little bit of zinc needed to keep those flat tappets and cam happy.

In your neighborhood's winter, you might consider the 12W40.

I run dino / mineral oil. The thinner and slicker synthetics often create oil leaks by getting past the OEM seals in the engine and drive train.

Suggest you change ALL fluids -engine, trans, driveshaft and final drive- to set your maintenance benchmark. Be sure to add a new oil filter, shim and o-ring to the job.

As to that zip tie on the diff's boot... that may very well be your leak source. There should be the proper metal clamps on both ends. What occurs with a Zip is a small, unclinched spot right where the strap passes through the locking portion. You'll never get it snug enough to stop weeps, seeps n' leaks.

BTW, gear oil stinks. Easy identifier.

[lukasgrech]

Cheers.

Does 'part-synthetic' count as mineral oil?

I plan on doing an all-fluid change asap.

Do you think I should go through the entire boot change, the surface of those blisters seems quite cracked, or should I just try to change the zip tie to the proper metal clamp?

[montmil]

... Does 'part-synthetic' count as mineral oil?

Only partly so. [smiley=whistling.gif]

[montmil]

Do you think I should go through the entire boot change, the surface of those blisters seems quite cracked, or should I just try to change the zip tie to the proper metal clamp?

Changing the driveshaft boot can be a life changing event.   No, not really, but it is necessary to detach the swing arm by removing the bearing pins and then separate the u-joint from the trans drive flange.

Properly orienting the new boot and getting it onto the seating areas -front and rear- usually results in several choice words and perhaps a wee bit o' blood. Then getting the metal bands to meet and threads engaged, well, more words.

New u-joint bolts -the short versions- are installed without washers and should be torqued as close to spec as you can get 'em.

Suggest you invest in a shop manual. Haynes or Clymer or both; as each manual has a few errors that the other can help explain away. Study the entire process and take your time with the boot install. Accidentally poking a hole in the new boot with a small screwdriver is an unhappy event.

Try the correct metal clamp if you wish. That's a quick way to discover if there's a hidden tear in the old boot or the zip tie was just a quick qhetto fix that didn't work.

[lukasgrech]

Mineral oils are a bitch to track down in town. Might have to order it online.

I will try the quick fix with the metal clamp and re-fill all the fluids and see  if the leakage stops - I would like to avoid teaching myself new words, for the moment

[Barry]

Does 'part-synthetic' count as mineral oil?
 

I've being running engine oil with with a 30 % synthetic content (and that's a lot more than some so called semi-synthetic oils) without noticing any problems with seals leaking.

By way of an experiment for my next change before winter I have some full synthetic to try. It will either stay in the engine or it won't and I'll be sure to report back which it is.

[lukasgrech]

Thanks Barry. Think I'll give this a try: http://www.halfords.com/webapp/wcs/stores/servlet/product_storeId_10001_catalogId_10151_productId_263777_langId_-1_categoryId_165507

From look and feel alone, the oil already in the engine doesn't seem to be very viscose anyway, so looks like I'll be ok with that choice.

[Barry]

That looks like good stuff. Castrol describe it as part synthetic and it has the SJ rating that Monte mentioned.

Dear though !   Just as well you only need 2L  for an oil change.

[steve hawkins]

You should be able to buy 5 litres of usable semi synth in a supermarket or down BandQ.   You do not need to use motor cycle oil as you do not have a wet clutch.  And your engine only revs to 7000rpm.

The oil is only going to be in there form 5000 miles.  Halfords is really over pricing its oil.

Save yourself a fortune...Or in this case get 2 oil changes for half the price of one from Halfords.

cheers

Rev Light

[Barry]

I buy my oil in bulk when it's on offer.  When I had more cars at home I bought it in 25L drums at £2-£3 litre.

For UK users http://www.eurocarparts.com/car-engine-oils have some good deals and do free delivery.

[lukasgrech]

Thanks for the oil tips, I'll have a look around before I spend that much money on half an oil change!

And now, digging deeper...

1. Rear bevel drive oil - practically empty and coffee with cream coloured. I believe the level is meant to be up to the bottom of the filler thread?

2. Drive shaft oil - NONE. Checked with a dipping stick and seems to be dry.

3. Gear box oil - Came spewing out when I opened the filler plug. Again, I'm given to understand that the level here should be just at the lower point of the filler plug.

Re. colour of bevel box oil, according to Snowbum's site, this means that water could be leaking in via speedometer boot (quite likely - rubber looks beat and now grease or silicone anywhere - will replace and seal up). However, he is referring to driveshaft oil. I am not yet familiar with the details of the construction of the final drive assembly, but all of this seems to me like things are leaking into one another, and leaking away too, since the levels are extremely low.

More worrying is that the PO had oil added to drive shaft and to bevel box, about 300 miles ago.

And finally,

4. The oil that is seeping from the swingarm rubber boot is indeed gear oil - it does not smell as strongly I thought it would, but a smell test comparing it to engine oil leads me to believe it is indeed gear oil. The large excess of oil in the gearbox could explain why this is ending up leaking from the inside of the boot out.

Where the hell do I start?