Oil Tech . . .

by **Admin** Sat Mar 12 2011, 00:47

Aircooled engines recommend a good 15w/40 which should be replaced every 3500 miles.

Information provided by Opieoils - www.opieoils.co.uk
(Aircooled Konnection club members receive 10% discount on Opieoils products see club members area for details)

Winter Months - it’s beneficial to use an oil that has good cold start flow properties as it will get to the parts of the engine that need it far more quickly when you turn the key on those sub zero mornings.

The "w" number which means winter is the key here and the lower it is the better cold start performance the oil will have.

A 15w or 20w rated oil will struggle to get around the engine in very cold temps and we would strongly recommend using a 10w, 5w or 0w for better cold start performance.

It is a fact that around 90% of all engine wear occurs on cold start because the oil is at its thickest. The colder it gets the thicker the oil becomes and this affects the rate of flow which affects the rate of wear.

These numbers help to explain the oils thickness and therefore cold flow performance at various temperatures.

Grade.................At 0C.................At 10C..............At 100C

0W/20.............328.6cSt...............180.8cSt............9cSt

5W/40.............811.4cSt...............421.4cSt............14cSt

10W/50............1039cSt...............538.9cSt............18cSt

15W/50.............1376cSt..............674.7cSt............18cSt

20W/50.............2305cSt...............1015cSt............18cSt

Centistokes (cst) is the measure of a fluid's resistance to flow (viscosity). It is calculated in terms of the time required for a standard quantity of fluid at a certain temperature to flow through a standard orifice. The higher the value, the thicker the oil.

Winters in the UK are fortunately not too cold but, below zero temperatures are regular features in some parts of the country.

Compare the thickness of the oil at 0degC and 100degC and you will see the big difference.

Just something to consider on those frosty mornings.

The Opieoils Team.

by **Grizzly** Wed Jul 11 2012, 19:22

Interesting take on VW aircooled oil . . . courtesy of The Samba

I have seen and replied to countless posts
noticing a fairly common thing. People are just completely clueless that
oil weight has a huge effect on your oil pressure and temperature.
Probably more of an adverse effect that having an undersized or over
sized oil pump does.

Now as I've stated in a previous post, I cannot take credit for this. I
read a post from John@aircooled which kicked me into gear experimenting.

I've found that depending on what you've got... case type, bearing
condition, oil galley size, single relief/dual relief,
doghouse/non-doghouse coolers, external coolers and oil pump size all
may require different oil weights for optimal cooling efficiency.

From the amount of testing I've done I have come to these conclusions;
1) 10w30 is the most commonly used oil weight and in about half of the
engines I've checked, 10w30 is the best weight for them. These cases
tend to be late model dual relief cases with 15mm oil galleys and a 26mm
oil pump.

2) Single relief cases, especially those with small oil galleys LOVE
light oil. 0w30 or 0w20. I use 0w30 because Brad Penn makes this weight.

3) I have not found one engine that needs 20w50. People seem to come to
the conclusion that heavier oil cools better which, well it might be
true. I don't know, but that thick of oil causes excessive oil pressure
in ACVW engines which makes the oil bypass the oil cooler. No oil cooler
= hot oil. Though it may or may not cool better, it does not work well
in air cooled vw engines. The only time that thick of oil should be used
is if you have excessively low oil pressure as if your mains were on
their last leg or your oil pump needs replaced. Using 20w50 is a
band-aid, not a fix.

You need to keep in mind, this is something that needs to be
experimented with. I've had engines that the overheating issue was
obviously caused by the oil pressure. Even with testing different
weights I didn't get them down to where they should be so testing the
weights might also include changing your 21mm oil pump to a 26mm or vice
versa. I know it sounds like a lot of work but on engines with NO
overheating issues I have commonly dropped the oil temps 15 degrees at
65mph... this is huge. My coolest running case is... are you ready for
this? A single relief H case with 10mm oil galleys, 26mm oil pump using
0w30. It used to run 230 degrees at 70/75mph and I couldn't run it for
more than 10 or 15 minutes at that speed which is about normal for an
ACVW but once I switched a few things around, now its running 215/220
degrees at 75/80mph and I can run it for hours at this temp. Pretty cool
huh? Pun intended.

This testing is pretty straight forward. Use 10w30 as a base line and
having an oil pressure gauge makes it much easier but if not you will
just be dropping oil a bit more. Make sure your oil pressure stays
within range. The 10lbs per 1000RPM rule is good to stick by,
Performance engines can have a bit more pressure.

Before even thinking about this testing you need to be sure you have ALL
OF YOUR COOLING TINS! Yes... sled tins as well. Stock VW cooling
systems are cheap and cool the best without spending too much. If you
have a cheapo aftermarket shroud(commonly 36hp style), ditch it. They
cool terribly 90% of the time and chances are they are causing most of
your issues.

I think that's about it....

by **Grizzly** Fri Jul 13 2012, 19:16

Seems we can use synthetic oil now too . . . see this article

http://www.aircooled.net/synthetic-vw-oil/

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