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The old oil chestnut again
#1
I know, I know, we've been over it time and time again, but I'd just like to ask this particular question...

Has anyone ever used fully synthetic oil in an A7 engine? The reason I ask is that I wheeled the RP out of the garage this afternoon and took it for a run, but even with a fully charged battery the starter motor was struggling to turn the engine over. I ended up having to bump start it down the drive because I couldn't even spin it over fast enough on the handle. The sump contents at the moment are 20W-50 multigrade, which works fine in summer, but seems very viscous at freezing temperatures (it was 1°C here today)

Once the engine was thoroughly warm it would start no problem on the starter.

I was thinking that a fully synthetic would resolve the cold starting problems, but would it be suitable for splash feed?
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#2
This would appear to give the best of both worlds.  20/50 viscosity and synthetic with lots of ZDDP as well.

https://www.opieoils.co.uk/p-77374-mille...ology.aspx

However if the oil is too thick from cold then either a wider range (I think that Penrite make a 20/60) or a fan heater on the sump for 20 mins before a cold start are tw best routs.

Charles
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#3
Reckless,
You need another earth from starter motor back to battery. On second thoughts you’ve probably already done that. Iv’e done it and it makes a big improvement. Alternatively, you could move a little further towards the Med.
Always like to help a pal!!
Dave.
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#4
Already got the extra earth, Dave. I am beginning to wonder whether the problem is actually the battery itself, even though it's connected to the accumate to keep it topped up. With only three cells for your 6v it doesn't take much wrong with one of them to knock it's duck off.

I'm going to try it again tomorrow, after having had a good run round on full dynamo re-heat & afterburner today and we'll see how it goes.

I think a new battery will be cheaper than moving to Marbella.
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#5
(17-12-2017, 07:20 PM)Reckless Rat Wrote: I think a new battery will be cheaper than moving to Marbella.

Good to see that whilst you can take the man out of Yorkshire, you can't take Yorkshire out of the man!

Think that Dave might have a point though, Bruce Cool

Steve
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#6
(17-12-2017, 05:59 PM)Charles P Wrote: This would appear to give the best of both worlds.  20/50 viscosity and synthetic with lots of ZDDP as well.

https://www.opieoils.co.uk/p-77374-mille...ology.aspx

However if the oil is too thick from cold then either a wider range (I think that Penrite make a 20/60) or a fan heater on the sump for 20 mins before a cold start are tw best routs.

Charles

On the Russian front in WW2, fires would be lit under the engine nacelles of Bf 109s and Fw 190s for just this reason!

Arthur
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#7
From the graphs in book Which Oil,  except at very cold temps multigrades are surprisingly thick. 20w50 at 0C is much thicker than 30. 20W60 would be worse.
Nevertheless decades ago when my car was everyday transport I spent a winter in Dunedin at south of South Island (although still a moderate latitude cf UK). The car lived on the street with regular frosts and started OK every morning using XL or thicker, although crank speed modest.
I suspect the relatively thick oils originally recommended predated anti wear additives.  Thick oils were also largely to reduce noise and consumption.
 
Presumably there are readily available inexpensive thinner oils 15W40 etc with 1980s or later API ratings.
 
For a low annual  mileage oil burning filterless Seven, expensive synthetics a bit like “feeding chocolate to pigs”. (An expression I picked up decades ago. A very senior govt engr got into deep poo for using it to describe the proposal to use CNG for electric power generation. Which NZ did anyway. For a period it was popular here for cars. I tediously adapted my 1950s model. But cars became too complex to adapt, the power loss was considerable with moderns,  and the whole vast industry collapsed before I had saved the cost of the kit!)
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#8
I use straight 30 oil. One reason being that it is thinner than most multigrades.
If using a multigrade I would look for a 10/30 but that seems very rare nowadays.
Any modern oil will be a lot better than those available when the carts were new.
Jim
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#9
I am slightly confused by this thread. I thought the whole idea with a filterless, splash fed engine was to have a non detergent thin oil which would find its way as quickly as possible to the big ends on start up, and would deposit any crud it picked up in the bottom of the sump, rather than carrying it around in suspension?
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#10
Fundamentally, you are right Colin, but when you rebuild an engine from scratch, you have the opportunity to get it internally as clean as a whistle. At that point, 20/50 is a perfectly reasonable option, but it is still worth changing it on a regular basis..

hth....
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