Synthetic v's Semi-Synthethic

Submitted: Monday, May 14, 2007 at 11:00
ThreadID: 45456 Views:5858 Replies:8 FollowUps:1
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Morning all, I was hoping for some opinions on the differences I might experience from going from a Semi-Synthetic oil (Penrite HPR10) to a fully Synthetic oil (Penrite or other). The vehicle is a 2000 Jackaroo V6 (3.5L DOHC) with ~120k on the odo.

I have been happy with the Semi-Synthetic Penrite, but was in Repco looking to buy oil as it's come round to servicing time again and I was wondering what differences (if any) I would experience in engine performance/fuel consumption/oil consumption/engine longevity etc. etc. going to a fully synthetic

Thanks in advance for any input you may have.
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Reply By: Gronk - Monday, May 14, 2007 at 12:59

Monday, May 14, 2007 at 12:59
NONE !!!!!! The oil you're using is pretty good so a small step up to fully synthetic won't make any diff ( won't do any harm either )
AnswerID: 239919

Reply By: Robin - Monday, May 14, 2007 at 14:02

Monday, May 14, 2007 at 14:02
Very little performance difference GAV.

Still I would only use synthetic's , particularly in gearboxes / diffs where its more noticeable in my GU patrol

Some synthetic's like shell Ultra are usually sub-$50 at Big-w etc so I don't find them to costly.

(Repco is expensive)

Robin Miller
Robin Miller

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AnswerID: 239927

Reply By: SimonW - Monday, May 14, 2007 at 16:23

Monday, May 14, 2007 at 16:23
Hi Gav,
I had a 97 Jack (3.2ltr) & ran Mobil-1 full synthetic from its first service when the vehicle had approx 90K on the clock I would start to get hydraulic lifter rattle on start up for approx 15sec but not every time, as you can imagine the dealers response, "new lifters" $$$'s, however I was advised by a local mechanic to drop down to a semi-synthetic ie: Mobil-S as the vehicle had done over 100K, & the change was instantanious & never had the issue again, sold the vehicle with 180K+ & it had never missed a beat. just my thoughts.

regards Simon.
AnswerID: 239946

Reply By: Olcoolone (SA) - Monday, May 14, 2007 at 18:24

Monday, May 14, 2007 at 18:24
I would use a good mineral oil instead of synthetic's.

You will never acheive the benifits of synthetic oil under average driving conditions, mineral oils have come along way in the last decade and there is not no benifits going to a synthetic oil.

If you have synthetic oil in your engine and you are running low you only can top it up with synthetic oil.....many be a problem if you are away.

Its a brillant marketing ploy isn't it!

A good quality mineral oil is as good as an expensive synthetic oil.

It all depends if you want to waste another $20 plus dollars on something you will not see a benifit from.

It happened in camper trailer suspension, one maker used indipendent suspension and marketed it as being fare better the leaf spring every other manufacture had to do it to.......when the case was there is very little differance.

Next you will sy nitrogen is better in tyres then compressed air...LOL.

Regards Richard
AnswerID: 239971

Follow Up By: anglepole - Tuesday, May 15, 2007 at 09:05

Tuesday, May 15, 2007 at 09:05
I agree. Holden recommend a CF CH engine oil for their Diesel Jackaroo.

10w-40 worked well in my 98 Diesel. If you change the oil every 10k a mineral oil meeting specs is the most effective cost option.

At 100k I had the engine oil analyzed at a commercial laboratory (Amdel) and the motor showed practically no wear.

I was using BP Vellanus Plus (spelling may be suss)

Hope this helps
FollowupID: 501063

Reply By: gav99x - Tuesday, May 15, 2007 at 08:52

Tuesday, May 15, 2007 at 08:52
Thanks very much for all of reply's everyone, looks like sticking with the HPR10 will be the way to go.

AnswerID: 240089

Reply By: Olcoolone (SA) - Tuesday, May 15, 2007 at 09:40

Tuesday, May 15, 2007 at 09:40
Its all to do with marketing.......unless its being used in extreme conditions.

Regards Richard
AnswerID: 240095

Reply By: Chaz - Wednesday, May 16, 2007 at 06:46

Wednesday, May 16, 2007 at 06:46
Like most things, you get what you pay for, but in most cases (engines) a good mineral or semi synthetic is good enough. In the case of a more highly stressed engine, synthetic is good insurance, but the important thing is to stick with the right rating and grade. Some manufacturers suggest tripling oil change intervals with synthetic. With your engine this isn’t so important.
AnswerID: 240252

Reply By: Robnicko - Friday, May 25, 2007 at 11:55

Friday, May 25, 2007 at 11:55
I had sent an email to Penrite regarding going from HPR30 (mineral) to HPR15 (semi-synthetic) in my 80 series landcruiser.
Here is a copy of Penrites reply,


Thanks for the enquiry.

While there is no problem in going from HPR 15 to HPR 30, if the HPR 30 is working well for you, you may as well stay there.
Semi synthetics do not cause any problems if a mineral oil was used in the past. Differences in additive chemistry can make more of a difference (not the case here) but even that is limited to short term oil consumption which goes away after a subsequent change.


Tony Lawton
Technical Manager
Penrite Oil Company

AnswerID: 242279

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