Which engine oil VN commodore late 89/early 90

[zai]

Hello,

which oil for my commodore:

1) 15W/40 SF (as indicated in the work shop manual)

Or

2) 20w/50 for older engine (as Castrol GTX 20w/50)

or

3) other oil for modern engine? (as castrol GTX 15w/40 SAE)

Thank you

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[chief18]

Here's a chart, the viscosity of the engine oil you choose depends on a few things, one being the outside temperature.

To thick an oil, cold morning...oils at its thickest, hard to pump around...to thin an oil..hot afternoon...oil thins out.

To thick an oil, is as bad as to thick an oil.

The other of course is the engine itself.

Older engines, the oil galleries are larger, hence thicker oil.

Newer engines, smaller oil galleries, thinner oil.

We use 20-50 for pre 2000 engines (GENERALLY) unless otherwise requested. Basically because it does the job and it's cheaper than 15-30/40 etc.

Any of the three you have listed would be fine, so it's more about your pockets, and preferance. Monitor how each oil effects your oil pressure throughout the temp range..you may find oil pressure takes 5 seconds to pick up when cold with 20w50, but you lose to much pressure when hot with 15w30, which would lead you to 20w40, which is in between.

[zai]

Ok thank you, I was a bit afraid because my last oil was not as advised in the workshop manual.
Was the 15w/40 castrol gtx.
As my car is a bit old, I prefer to service it with the advised components
++

[levymetal]

To thick an oil, cold morning...oils at its thickest, hard to pump around...to thin an oil..hot afternoon...oil thins out.

might want to take that back to the drawing board. no such thing as a 'thick' or 'thin' oil. there are 2 ratings for oil, 1 when cold 1 when hot. i use a HPR 15: 15w60. easy enough to pump around when cold, and thick enough to keep the engine together when hot. you can't just say "oh it's a thin oil because it's got a viscosity of 15 when cold", or "oh it's a thick oil because it has a viscosity of 60 when hot".

[greenfoam]

Mobil one comes out of the engine like water so I call that thin :P

[LordMayhem]

i just use penrite HPR 30 always have always will

[Peter89]

regular, cheap thick mineral oil i use. waste of money putting any decent oils in the car.

[spark79]

i use castrol 5-30w in my vp s2 , my engine dosent use oil or leak oil , i use genuine filters , i've had no probs yet,