Upping viscosity in my commodore

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Hi guys and girls
Currently in the process of doing my valley cover gaskets as i need to flush the old contaminated oil out i was thinking of going from 15w40 to 20w50 0r 15w50, yes the commodore has seen better days and i need to make the engine last for atleast another 4 years. As it sits it has sone 336,430 klms and has been on LPG since 2008 unknown k's when it was put on LPG as i bought it with no service history. Last service i put in Shell Helix HX5 15w40 (because it was on sale at supercheap) i was thinking of switching to Castrol GTX 20W50 or Penrite HPR Diesel 15w50
Thanks in advance
 
Is your engine burning oil? If not, then I wouldn't worry. If so, I would try an Xw40 hm oil for a couple of oil changes. If that does not help, check for oil leaks outside of the engine. An Xw50 should be fine. 336000 KM isn't all that much. Around 210k mile in American terms. As long as everything runs fine, oil related issues would be the last of my worries.
 
I read when you run cars off LPG you need to run a tank of gas every few tanks to clean the valves off or else you'll get carboned up valves
 
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G'day Mate,

I think the modern mineral oils like Castrol GTX 15W40 and Shell Helix HX5 15W40 are good quality and good value for money. They are both American API SN and Euro ACEA A3/B3, two very good and up to date specs. Thread here
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4293744/1/

I find most 20W50 oils only carry older specs like API SJ or SL, so I tend to avoid these now days. The one exception is Valvoline MaxLife 20W50, it's a semi-synthetic that is SM and A3/B4.

I also avoid most 15W50 oils, as a few formulators here have commented that they tend to be a 15W40 with a higher polymer VII load, so nothing special, and better off sticking to the 15W40. I tried a 15W50 once and it didn't do me any favours.

What I do like is mixed-fleet HDEO's like Castrol RX Super 15W40, a stout mineral oil made for both petrol cars and diesel trucks. They are thicker than the regular PCMO 15W40, high zinc and rated API CI-4+ / SL and ACEA E7. Good strong stuff.

I also like Penrite HPR 30 which is a mineral 20W60 that is high zinc (anti-wear agent) and a top quality oil. I've run this in my old air-cooled motorcycles, and while GTX 20W50 sheared out and went bad in a few months, the HPR 30 held together and went the distance. It's SM and A3/B3. The HPR 30 was also my oil of choice when driving my old 202 Kingswood through the outback, and the only oil that stopped consumption on my old Audi where 15W50 would burn off like water.

Here are some local sales:
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4347486/
That Penrite Vantage looks like good stuff to me.
Quote:
At Repco in Australia, 9 to 19 March.

Penrite Vantage 15W40, semi-synthetic
It's API SN and ACEA A3/B4
60% Off, $20 for 6L
KV100 = 14.8 cSt
Zn = 1090 ppm
SA = 1.29 %
TBN = 10.1
 
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And just to have it all in one place....

Shell Helix HX5 15W40 (SN / CF & A3/B3)
KV100 = 14.27 cSt
KV40 = 106.0
PP = - 45C
FP = 241C

Castrol GTX 15W40 "Modern Engine" (SN / CF & A3/B3)
KV100 = 14.5
KV40 = 113
PP = -36 C
TBN = 8.3
HTHS = 3.95 cP

Penrite Vantage 15W40, semi-synthetic (API SN/CF, ACEA A3/B4, VW 502/505, MB 229.1)
KV100 = 14.8 cSt
KV40 = 109 cSt
Zn = 1090 ppm
SA = 1.29 %
TBN = 10.1

Castrol RX Super 15W40 HDEO ( API CI-4Plus / SL & ACEA E7)
KV100 = 15.9 cSt
KV40 = 125
PP = -33C
FP = 210C
SA = 1.39
TBN = 10.9

Penrite HPR30 20W60 mineral ( SN, A3/B3, VW 502/505)
KV100 = 24.2 cSt
KV40 = 229 cSt
Zn = 1570 ppm (ZDDP)
SA = 1.29 %
TBN = 9.7
 
Originally Posted By: E150GT
I read when you run cars off LPG you need to run a tank of gas every few tanks to clean the valves off or else you'll get carboned up valves

That is not correct. I've had vehicles go hundreds of thousands of miles consecutively without one tank of gasoline, and the valves were clean. LPG was unkind to older style valves, particularly when hardening for unleaded fuel was in its infancy, but carbon wasn't an issue.

A bit of carbon on them might have been helpful.
wink.gif
 
Originally Posted By: Tommyboy97
or Penrite HPR Diesel 15w50

I've never used that one, but it looks OK to me. It's a semi-synthetic, and being diesel it should be shear stable compared to a PCMO 15W50

Penrite HPR Diesel 15, 15W50, semi-synthetic (API CI-4/SL, ACEA A3/B4 & E7, and lots of OEMs like MB 228.3, Volvo VDS-3, etc)
KV 100 = 19.7 cSt
KV40 = 166 cSt
Zinc = 1220 ppm
SA = 1.34 %
TBN = 10.7

Also I've just noticed that Castrol have updated the GTX 20W50 data sheet. Last year in 2016 it was API SL, but now in 2017 it's API SN.

GTX 20W50 API SL
KV100 = 17.6 cSt
KV40 = 157 cSt
SA = 0.98 %
PP = -36 C
FP = 215 C

GTX 20W50 API SN/CF
KV100 = 18.3 cSt
KV40 = 171 cSt
SA = 0.8 %
PP = -30 C
FP = 201 C

I would go the high TBN, high Zinc, high Sulphated Ash Penrite myself, out of these three 50 grades. That's if you want a 50 grade.

If your not consuming oil, I would go the Penrite Vantage 15W40 semi-synthetic that is on sale right now. I would use it even is not on sale. Just my 2 cents.
 
Spec for my VS Caprice per the manual (I've got the supercharged 6 but was same for all of them) was 20W50, with 15W40 for prolonged operation in the Snow.

Not using oil ?

Then a decent 15W40 will do you well, and even if you do use a bit, the Penrite Vantage special at Repco (per SR5s post will do you well).

If you want 20W50, then any of the brand names bought on special will suit too.
 
I'd say a 15w-40 will be perfectly fine for this engine (the '96 simply has an upgraded Buick 3800, correct?). If its the Buick 3800 V6 I think you've got - the ejavascript:%20void(0)ngine would spec. an xW-30 in the USA - but the extra thickness won't do any harm at this point.

Bear in mind LPG is a much cleaner-burning fuel than Petrol (gasoline), so contamination will not be anywhere near as great. With that considered, diesel oil is almost certainly overkill. The only thing worth considering about LPG is it is a very "wet burning" fuel, so excess moisture in the oil could become an issue if you only short-trip the car.

At the end of the day, you've got a nice simple car that gets you from A-B. I'd certainly suggest driving it "until the wheels fall off."
Also interesting you note no issues with the LPG, I've certainly rumours the Commodores don't take well to LPG, but have a mate with a similar-aged ute that runs on gas only, no issues and goes like stink.
 
Considering the Buick 3800 V6 (what's used in the Commodore) would've carried a 10w30 recommendation in the U.S.A., I'd probably suggest 20w60 is overkill unless you have major oil burning issues or thrashing the engine with performance mods. Something in the xW-40 grade can usually be had for a steal if you keep an eye out for sales at Supercheap and the likes.

A mate of mine has a similarly-aged Commodore with dual LPG tanks, plus the factory petrol tank (fuel pump dead, and buried underneath gas tank, so its dedicated LPG presently). Mileage stands around the same as yours, too. The automatic has just had a rebuild, and the thing will still easily spin its' wheels. Much as I rag on Commodores in particular, they certainly have a decent drivetrain in them.
 
I spoke to my brother in law who is an expert in all things automotive (he has a diploma in automotive and the experience to match) he said because it so old, the high k's and I recently compression tested it and its right on the minimum spec so that's why he suggested the gas 20w60
 
Quote:
Considering the Buick 3800 V6 (what's used in the Commodore) would've carried a 10w30 recommendation in the U.S.A.............,

Bearing in mind this recommendation is CAFE/policy-driven .... which I would ignore ..... in OP's context.

Originally Posted By: Tommyboy97
I spoke to my brother in law who is an expert in all things automotive (he has a diploma in automotive and the experience to match) he said because it so old, the high k's and I recently compression tested it and its right on the minimum spec so that's why he suggested the gas 20w60

It makes perfect sense, though it's out of reach for me.
 
Originally Posted By: zeng
Quote:
Considering the Buick 3800 V6 (what's used in the Commodore) would've carried a 10w30 recommendation in the U.S.A.............,

Bearing in mind this recommendation is CAFE/policy-driven .... which I would ignore ..... in OP's context.

Maybe - but how many 1980s and 1990s Buick 3800s haven't gone the distance on 10w30? Time and time again, we've proven CAFE oil recommendations aren't causing en-masse engine failures from too thin an oil. Likewise, 20w60 won't kill the engine, but is probably the opposite extreme.
It makes me think of Shannow comparing the xW-30 recommendation (USA) to the 20w50 (Australia) recommendation for the Caprice.

While I respect the opinion of those with qualifications, the "thicker is better for old vehicles" mantra goes a bit too far in Australia. I don't think you'd have much luck finding xW-60 oils, except boutique racing/high-performance synthetics in the U.S.A. or Europe.

Sticking with OE recommendation is a good start. If you have "funny noises," thicker oil is only going to cover up the inevitable, in my opinion.
 
Originally Posted By: Garak
Originally Posted By: E150GT
I read when you run cars off LPG you need to run a tank of gas every few tanks to clean the valves off or else you'll get carboned up valves

That is not correct. I've had vehicles go hundreds of thousands of miles consecutively without one tank of gasoline, and the valves were clean. LPG was unkind to older style valves, particularly when hardening for unleaded fuel was in its infancy, but carbon wasn't an issue.

A bit of carbon on them might have been helpful.
wink.gif



^ What he said
laugh.gif


LPG engine should last a bazzillion miles if taken care of. You are doing fine with what you have. As suggested, maybe a HM oil in a good grade. Stay away from VII loaded oils. 15W-40 should be fine in your climate. Have you ever done a UOA?
 
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