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[doz]

Hopefully the brainier member here will be able to give me a suitable laymans answer. Right our old VW bus uses straight 30 weight oil. Now I've beefed up the engine just a wee bit. So instead of making 50 horses it's now a torquey 100 horse lump. I feel using 50 year old oil technology is a bit pants now so I want to use something more modern. Now I know the 30 of the oil refers to the viscosity at 100 C and is measured in Centi=stokes. I've looked at the values and can't see why I can't use a 10/40 or maybe a 20/50 oil but I'm not clever enough to work out the best one to use or even if I can. So come on all you oil gurus what can I use

[martin42]

personally i would go for the 10/40 semi,as its a modded lump but not ott where a 0/40 synthetic would be better for a heavily modded lump,could ask opie oils as they deal with oils etc

[doz]

Opie says 20/50 

[aaronjb]

I'm not 'up' on the old VW engines - I presume on your comments that it's the old air cooled engine?

Do you need an oil with high Zinc content to prevent wear to flat tappets etc? If so, don't use a modern oil or if you do, put some ZDDP additive in it..

[Kevin Wood]

The only reasons I can think of for using a straight oil are to reduce consumption when cold (maybe useful on a boxer where oil sits in the bores?), because it runs too hot for a multigrade or, as Aaron said, due to the metallurgy of the engine calling for a vintage oil.

Oil temperature would be my main concern on an air cooled engine that's been tuned, hauling a heavy vehicle along. Worth adding an oil temp. gauge, I'd have thought, and if the oil temperature is exceeding 120 degrees C or so, fit a cooler.

If it's being changed regularly, has the right additives and isn't resulting in excessive consumption, it probably doesn't matter, TBH. Certainly not worth paying "boutique" prices for antiquated oil technology IMHO.

[Marks DTM Calib]

Hmmm, agreed with above.

Although its been fettled, the fundamental engine design is unchanged, bearing clearances are the same, oil pump the same and the oil passages the same.

These engines are a mega comromise so I would be going for a modern mono grade ring free oil as per the original spec, given the extra go, I would probably be looking at oil coolers so as improve cooling

[barclay03]

I asked a mate... hes got an old splitty running 152bhp tuned by a company down south, and hes still running the 30w oil as it aids with cooling, although he cant rev it cold or it blows the filter lol

[doz]

Mine has another oil cooler fitted which is mounted under the bus with a fan should I ever need it. Not unusual to see 130 C on temp gauge but that was before the additional oil cooler and a deep sump kit which now means it holds 5lt instead of the poxy 2.5. I do have flat head followers if that's what you mean by flat tappets and there "bigfoot" ones which spread the loading more. I've also got ported and oversized valve heads fitted which I set up to increase the compression ratio to 8.2 from low 7s. So the engine will run hotter but the tinware and fan are now in excellent condition and well sealed so plenty of air getting pushed around. Agree air cooled lumps run hotter than their water cooled counter parts. Also the cam has been changed. Initially to improve mid rev torque but it also raises the rev ceiling from the poxy 4200 to closer to 6k. I had to use ratio rockers to get the required lift from the cam. on top of this  things like the oil pump have been upgraded. It's been a mammoth build and few head aches along the way  when it came to to setting compression,end float, push rod length and combustion chamber size. We've also beefed the gearbox up changing the ratios on 3rd and 4th to give a more relaxed drive. Engine size went from 1600 to 1835 as well and to cope I've fitted twin Kadron carbs with bigger ventures and jets to suit being supplied via Faclett eleccy fuel pump instead of mechanical. So it will be a bit strung out but as you can see I've tried to make it more reliable . I even improved the breather system The one thing which scares me is the first start after engine build. you have to rev it for 20 minutes at 2k rpm to do the "cam burn" Apparently if you don't do this the cams go to to chocolate in some cases less than 1k miles.  If somebody is running 150 BHP and still using 30 weight then I think it's fair to say mine will be ok. 150 is a lot I would think that lump must be well over 2lt's.

[barclay03]

No sure what the capacity of his is tbh... i know hes spane ta fair few bob getting it built though! Compay that did his said dont really have to go for heavier unless you're pushing 200+

[aaronjb]

If you had to run the cam in like that then I'd say it's a fair bet that you want an oil with a high ZDDP content; e.g. a 'classic' oil (like Millers Classic), not a modern multiweight low Zinc oil.

[doz]

Yea that makes sense now. I cranked the engine over the other day with the plugs outand the oil pressure went higher than when it use when it was running at 3k rpm!!! What I do like about these old buses is the electronics.......... there isn't any in fact the loom is only made up of about 20 wires in total. So refreshing 

[doz]

No sure what the capacity of his is tbh... i know hes spane ta fair few bob getting it built though! Compay that did his said dont really have to go for heavier unless you're pushing 200+

I've spent close to 2.5k on the engine and box and that's with me doing all the work. So I'm guessing your mate probably spent double that. Wreckon his might of been built by state side tuning. Excellent engines but god they cost a pretty penny