Engine oil

Hello and merry Christmas. I'm after some recommendations for engine oil for my 9A engine. Would 10w40 be suitable? Looking at Castrol magnatec. I'm sure the the garage who done my engine conversion used ow30 semi synthetic. I could be wrong. Isn't this a bit too thin? What do you use. Cheers

I have used 10w40 or now 20w50 on all my 4 bangers since the 70's, with the Exception of my 81 Golf Diesel which used 10w30 cc/cd.

I even used it in my V8's and V6's with no ill will.

I would recommend no Generic or Store branded filters, and the only one I trusted on my Cabriolets were:
STP
Mobile1
Mahn
Mahl
Genuine VW
Wix.
No Fram, or Bosch, as they caused blinky oil lights at idle.

 

When the VW technical manuals for Mk1 Golf, etc were last updated in the early to mid 90s, for petrol engines, VW specified oil complying either with VW oil specification 500.00 ("improved lubricity oils"), as used in the factory, or the lower spec VW oil specification 501.01. With improvements in oil technology, 500.00 has been superseded by 502.00, and 501.01 has pretty much fallen by the wayside.

For the old 500.00 standard, 5W-30, 5W-40, 10W-30 and 10W-40 were all listed as suitable for the full ambient temperature range of between -30 deg C and +35 deg C. Oils meeting the lower 501.01 standard typically covered a slightly narrower ambient temperature range, depending on viscosity.

In conclusion, any oil meeting VW's current 502.00 standard for petrol engines should be suitable, regardless of viscosity range. The equivalent standard for diesel engines is 505.00. Many mid-market and premium oils meet the standard - often abbreviated to VW 502/505 or similar - check the back of the container or the data sheet online. Also check the manufacturing date on the container, as shelf life is usually only 3 or 4 years.

Edit: Just noticed you mention the 9A engine, not an original fitment on the Mk1 Golf, but from the same era, so 502.00 would still be the oil spec to look for. It's only when you get to later technologies, such long life servicing, PD diesels and some recent TSI engines, that more specific later spec oils are needed.