Thread: 6VD1 engine oil

Hi all. I'm about to do a oil change on my Rodeo with the 6VD1 engine, owners manual says to use 20w50, seems a bit thick for this type of engine, but every website I've checked says 5 to 10w30. Repco and supercheapauto website list almost every grade of oil so they aren't much help. Are there any 6VD1 owners in this forum and if so, what do you use? Thanks.

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It is all to do with the ambient temperature when you start up a cold engine.... if 20W50 may be suitable in the hot Aussie outback... but a Canadian winter would need 5W30... and maybe an engine heater.
For NZ 15W40 will see you right for cold mornings down to a minus 10C minimum.

Basic knowledge, easy info to source which any mechanic, which I was under the impression OP was, should know. Remembering of course that modern close tolerance engines tend to run lighter oils.

Head through to one of the oil company websites that specify the type of oil you need for an engine using their website check tools or charts. You should get a temp range for each grade of oil, normally there are four or so options from desert toice. If the engine is older with a bit of wear you might be able to drop a grade for one thicker, but need to give a few minutes at idle for warm up time before you start using it...

Here is a little chart I made up to plot the viscosity index of some common engine oils.

The layman needs to keep in mind the engine and oil temps when running and stable, are largely constant, controlled by the coolant thermostat. If the coolant runs at 85C the oil will be somewhere between 90C and 120C.

The only big viscosity variances we see, are at the start up.... as you see below... at operating temps there is very little viscosity difference between all the grades. Having said that, if you have a range of viscosities to choose from, lean to the above average viscosity options to provide greater film thicknesses and strength. Especially so if in severe applications like pulling a plow all day.

Did some searching on oil company websitesas @No.3 suggested. Here are the results (pics below).
Penrite recommends as thick as 20w60 mineral. I have used Gulf Western 20w50 mineral but it really dirties up the engine. Penrite do suggest 15w60 synthetic, 60 still seems too thick.
Gulf Western recommend 15w50 and 20w50 synthetic but no mention of 20w50 mineral. The reason I have used mineral is because it was recommended by a supercheapauto staff member after looking on their computer.
Nulon recommend 10w40 and 15w40 synthetic. Nulon website lets you select the state, only Australian states, no NZ, so I selected Tasmania seeing it would have a similar climate to NZ



I find if odd that a modern engine like a 3.2L v6 would use such thick oil like 20w60, even in OZ.
I'll probably go with 10w40 or 20w50 synthetic depending on cost but if I go with 20w50 I'll change out to 15w50 when winter rolls around

Does it burn oil?

I find it odd too - that doesn't seem to tally with anything I've been recommended in NZ. More modern engines tend to run 5w-30 full synthetic, but the petrol in yours would not be requiring that I would have thought. Of what you listed the 15w-40 multigrade semi synthetic would be probably what I would be looking at, as it splits the difference between the 20w50 in the manual and the 5w30 that everyone else is pointing to.

But - and it's a BUT - the SAE viscosity rating of the oil (eg 20w-50) is only part of the equation. There's an ACEA or API classification that also specifies what grade of oil you need for your model of the engine. It will be something like ACEA B3/B4 or C3/C4 or API SL or CF etc etc. You really need to get this right as it ties into the film thickness of the additive packs in the oil and how it responds to friction and heat of the engine when it's in operation. I can't tell you what this is as I don't have the engine info from yours here - but you've got quite a few different spec oils there and I'm not sure from what you're looking at what the right option will be.

Could be worth asking the local Isuzu or Holden place what the actual spec is they recommend for your engine or getting a quote from them for a service kit just so you have it.

Originally Posted by blip

Does it burn oil?

Not really, weeping a little out of the rocker covers

Originally Posted by No.3

I find it odd too - that doesn't seem to tally with anything I've been recommended in NZ. More modern engines tend to run 5w-30 full synthetic, but the petrol in yours would not be requiring that I would have thought. Of what you listed the 15w-40 multigrade semi synthetic would be probably what I would be looking at, as it splits the difference between the 20w50 in the manual and the 5w30 that everyone else is pointing to.

But - and it's a BUT - the SAE viscosity rating of the oil (eg 20w-50) is only part of the equation. There's an ACEA or API classification that also specifies what grade of oil you need for your model of the engine. It will be something like ACEA B3/B4 or C3/C4 or API SL or CF etc etc. You really need to get this right as it ties into the film thickness of the additive packs in the oil and how it responds to friction and heat of the engine when it's in operation. I can't tell you what this is as I don't have the engine info from yours here - but you've got quite a few different spec oils there and I'm not sure from what you're looking at what the right option will be.

Could be worth asking the local Isuzu or Holden place what the actual spec is they recommend for your engine or getting a quote from them for a service kit just so you have it.

All the American websites for the "Isuzu Rodeo" list 5 to 10w30 but sites I've checked for the Australian "Holden rodeo", which I have, is more or less 20w50.
I have to find the manual and check the acea/api classification, I know its "SJ" something.
I emailed NZ Holden, they don't know.

Castrol NZ website lists Magnatec 10W/40 or alternatively GTX 15W-40. User manual for sure will list correct oil. I find it hard to believe Holden NZ or a Holden service centre can’t tell you.

Id just put 15 40 in it, the repco brand oil is actually valvoline oil now

Originally Posted by Three O'Three

All the American websites for the "Isuzu Rodeo" list 5 to 10w30 but sites I've checked for the Australian "Holden rodeo", which I have, is more or less 20w50.
I have to find the manual and check the acea/api classification, I know its "SJ" something.
I emailed NZ Holden, they don't know.

API SJ is pre-2001 petrol engines if I remember right, API SL supersedes it and can be used in it's place. You can go forwards or more recent spec, just not backwards to older classifications.

If the engine is fairly good and not using oil, an API SL 15w40 semi synthetic multigrade should be fine - most of these are sold as diesel engine oils which is a harsher service for the oil. If the engine has been using oil, options are 20w50 in the same spec or run a flush product through it and try it on the 15w40 and see what happens. A lot of the time there's just a heap of crap in the oil rings and the like and a good flush gets it back to normal but the odd instance the engine is actually needing servicing and flushing it makes it use a lot more oil (wear in the valve guides or other parts and the flush process removes the stuff that is holding the oil in!!!).

Originally Posted by blip

Id just put 15 40 in it, the repco brand oil is actually valvoline oil now

Cool to know use to be penrite