Pre-serp , 10w50 or 15w50 oil?

I have a pre-serp V8 in a Rangie, it's normally a good starter, however it's become a lot slower to turn over in the current 0'C temperatures. I'm using Valvoline VR1 20w50, I have previously tried 10w40 but the oil pressure light would flash at idle when hot, so I want to use an oil that ends in "50", however it is possible that "20W" is too thick in freezing conditions at start up.

Has anyone used Penrite 10w50 or 15w50 semi-synthetic motorcycle oil (ZDDP 1200+ ppm) ?

Hi Mike,

You may be better off putting this question in either the Rangie section or the ina specific engine section. Otherwise it will quickly get lost in the engine forum.

Cheers

Thanks, I thought I'd posted this in the V8 sub-forum, but apparently not.

Battery fully charged?
Earth leads in good order?
Mine's a 3.5EFi & is on mineral 15w/40. No starting issues.
Isn't synth & semi-synth a bit thin for the V8s?

Ratae said:

Isn't synth & semi-synth a bit thin for the V8s?

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Yes it is, the design of these engines dates from the 'sixties, the oil pumps are hardly hi-tech & thrive on mineral oil.
I run my 3.5efi on Valvoline VR1 20w/50 or Millers Classic 20w/50 both having zddp of 1200 ppm & I don't have a cold weather cranking problem despite having a standard spec. battery & the car often being unused for a fortnight.

Can't see the oil pump slowing the cranking down that much. 10w 40 isn't ideal but within the range given in the manual, so I'd say get your oil pressure checked.

Grade wise they are the same oil SAE 50 I don't remember any issues using 20w 50 in the winter with my 3.5 RR or any cars before that. My 3.9 disco runs with 10w 40 always has done, still with out issues, it's basically the same engine.

Thanks for the replies, I'll give the 10w50 a spin. Cold starting has improved over the last couple of days, but then it has got warmer!

id personally go for a 20w50 as the v8s are an older type engine and have more tolerance then modern high tech v8's

i all ways use the 20/50 valvoline,1996 4.6 hse,my personal preference of course.

10W-40 or 15W-40 in diesel oil in our Thor V8's.

Peter