Author Topic: Engine Oil  (Read 3060 times)

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Offline whitewall

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Engine Oil
« on: December 05, 2013, 07:51:21 PM »
It has been a while since any engine oil discussions for the older Cadillacs. I have the 67 with the 429 engine with around 60,000 miles since last rebuild and find the thicker oils such as the 20w-50 oils are too thick especially in the cold mornings. Currently I am running the shell Helix HX5 LPG 15W-40 oil as the car has a Gas Research LPG system. I will be changing the oil to Castrol GTX diesel 15W-40 at the next oil change within the next week or so.

The manual recommends 10W-30.

The best oil experiences I've had was Caltex/Chevron Delo 400 multigrade 15W-40 which was a little too thick at cold start up but very sweet and smooth running at operating temp and Shell HX7 10W-40 which was very good at start up but a little noisy at full temp as well as using a little more oil.

These days there are a whole new series of oils with new ratings and I was wondering what kind of experiences people were having with these new oils.

I have checked out the Bob's the oil guy site but find the USA oils differ to Australian oils.

Offline Bruce Reynolds

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Re: Engine Oil
« Reply #1 on: December 05, 2013, 10:33:54 PM »
Firstly, whichever oil you use, use one with Zinc in it, as you are running flat tappets, and you NEED the Zinc in the oil to make these parts live.

The new oils without Zinc are designed for Roller cams and lifters, etc.   Anmd also are designed for the Anti Pollution crowd.

The 10 W 30 oils in the Manual are for when the engine is new, with tight clearances.   The Makers never thought these cars would be still going these days, and therefore there is no recommendations of thicker oils as clearances grow.

Now, how do you know that the 20 W 50 oils are too thick?   !0 W 40 oil is in my opinion too thin for a car with such mileage.

I would be talking to your local Oil Supplier, as I have had nothing to do with LPG powered vehicles, and they might use totally different requirements.   But, I do know that to get the best performance out of LPG, you need to run something like 12 to 1, or even higher compression.   But, if you are running dual fuel, then you have to compromise.

Bruce. >:D
Bruce Reynolds, Lindisfarne, TASMANIA
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
(Past President Modified Chapter)

Offline whitewall

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Re: Engine Oil
« Reply #2 on: December 06, 2013, 08:25:31 PM »
A couple of cold morning starts resulted in some high pitched metallic sounds. This happened two times and both times with 20W-50 oils. LPG does run drier than petrol and doesn't dilute the oil so it may be a factor.


Offline Bruce Reynolds

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Re: Engine Oil
« Reply #3 on: December 07, 2013, 12:21:38 PM »
Oh dear.   Can't assist any more, but I wouldn't be using incorrect oil in any LPG vehicle.

Bruce. >:D
Bruce Reynolds, Lindisfarne, TASMANIA
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
(Past President Modified Chapter)

Offline whitewall

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Re: Engine Oil
« Reply #4 on: December 07, 2013, 08:17:49 PM »
Changed the oil to Castrol GTX 15W=40 diesel oil yesterday and so far it seems okay. It feels a little smoother overall.

I believe the main requirements for LPG oils are low ash and higher flash point. The problem is there isn't much choice in dedicated LPG oils.

Offline Bruce Reynolds

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Re: Engine Oil
« Reply #5 on: December 07, 2013, 10:06:53 PM »
I would be having a talk to the Taxi Companies and see what they are using.

Bruce. >:D
Bruce Reynolds, Lindisfarne, TASMANIA
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
(Past President Modified Chapter)

Offline 60cad

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Re: Engine Oil
« Reply #6 on: February 17, 2014, 09:07:41 PM »
I have a 1967 caddy with the same engine , I run Valvoline XLD premium 20/50 which is high in zinc , it works well in my car
I know the Valvoline max life 20/50 being semi synthetic will suit the LPG , but it misses out on the zinc.
Hardly anyone makes a dedicated LPG oil now , You could find vr1 racing 10/40 which is also high in zinc but I personally think it's to thin ,
im in the oil business ,I know  XLD is the best