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Which Engine Oils?


kim

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Is there a big difference between fully synthetic oil brands? I have been running my xflow 1600 for the last 3 years on Shell Helix 5-30W. At £30 for 4 litres it is expensive compared to Comma Syner-G 5/40W fully synthetic at £20 for 5 litres. Can anyone out there advise? It's not that i want to be a cheap skate but why waste money if there is no discernable difference to the performance characteristics of different brands. Besides I understand that Comma sponsor Caterham!

 

Thanks in anticipation

 

Kim Mason

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According to Comma, SynerG 5w/40 is exactly the same as the discontinued Mobil 1 of the same SAE rating from a few years ago. SynerZ is the same as the current 0w/40

 

I run SynerG in my engine (280bhp Vaux) and having just dismantled it after 14000 miles without any work other than a bearing inspection I have found next to zero wear on all parts except the bronze valve guides (which have considerably shorter life than the iron variety fitted to all standard spec engines.

 

I think therefore thats probabky a recommendation.........

 

 

 

Arnie Webb

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  • 1 month later...

Use 20/50 of any variety. Valvoline Racing 20/50 is a good quality mineral oil. Millers do a semi synthetic 20/50. Both are less than £25 for 5 litres. Tran-x sell Millers (www.tran-x.com) and so do Triple S powder coating (www.triple-s.co.uk). Others must also, but not sure who. Burtons sell Valvoline.

 

John

 

John

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Er.......Cosworth specify 20W 50 for their 2.0L Turbo as fitted to Sierra's. I don't want to start another heated discussion about the why's and wherefores, but the Turbo Cossie also uses hydraulic followers, like some K's and Vx's. Based on the various opinions on here previously about oil thickness and hydraulic followers, as well as film strength, perhaps a modern 20W 50 isn't as bad as we think. I'm sure Cosworth spent a considerable amount of time in R&D determining specification for oil, especially when a Turbo is involved. JMHO and all that.
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I thought that Caterham specified 15W40 for the x-flows. This is well catered for by Castrol Magnatec for basic engines!!!! I have used this for the last 3 years or so with regular oil changes with no apparent detrimental effect to my engine.

 

My understanding was that fully synthetic was primarily aimed at extended service intervals and that almost any oil of the correct viscocity would work if it was changed regularly enough.

 

No doubt Roger King has ideas on this area, and for one of his precision built engines (rather than the South African built pump engines) a beter quality oil may have some benefit.

 

Donning Nomex underwear and standing well back....

 

Cheers

 

Graham

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Blatman - once up to running temperature a 20W50 won't be any different to a 5W50 or a 10W50. The number before the W is a measure of the oil's resistance to thickening in the cold, the lower the number the more resistant the oil is to thickening - so in cold climes, and if you do a lot of starting up from cold, then the lower this number the better.

 

The number after the W is a measure of the oil's resistance to thinning in heat. The higher the number the more resistant it is. In arduous conditions (like in a hard-used high-power engine, or in a hot climate) you want a good high number here.

 

Mike

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I understand about the viscosity numbers and their meanings. I was alluding to (badly I'll admit) the cold weather issue. I would want to know how much thicker a 20W is at 0 degrees c, compared to a 15W or 10W. Would it be that significantquestion.gif I used the Cosworth as an example due to the similarity of spec with regard to hydraulic followers, and the fact that Cossies are, potentially, used all year round, so would be subject to the lowest of temperature starts. I think it's fair to say that most of us use more sensible car's when it's that cold, although going out in temperatures not much above freezing is something lot's of us do. Given these thoughts, would a 20W be that detrimental, when compared to a 15W or 10W. And if it's just a percentage answer, ie 10W is half as thick as 20W, then no furhter explaination is required. Phewwink.gif
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When I posted 20/50, I still believe that I am correct. The original posting was asking for reference to a X-Flow, which thinner oils are not ideally suited to, due to the engines poor manufacturing tolerances.

Burtons recommend 20/50, so thats good enough for me.

 

John

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John,

 

Why would you want an oil that is thick when it is cold, even with the tolerances of a crossflow? I understand that an oil that stays thicker for older engines whilst it is hot is good and that to have an oil that stays thick whilst it is hot may be a little thicker when it is cold (!) but there seems to be little logic in having thick cold oil in your cold and vulnerable engine if you don't need to.

 

More to the point. Has anybody ever had a failure due to the wrong oil? I only know of one - that being Brian Fitzsimons who after discussing it with an oil company (I think) says he would NEVER put synthetic in a crossflow. Even Castrol RS which was pretty thick stuff. The reasons given were as I mentioned earlier.

 

Alex

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S'pose I might as well stick my oar in here.

 

If your Crossflow is in good condition then I personally would like to see it on something like a 10w/50. Unfortunately this seems to be a bit of an odd viscosity. In practice the Mobil 1 15/50 racing is excellent, especially if you're competing (and Halfords sell it). On the road we find that Mobil 1 0W/40 seems OK, but Comma Syner G at 5w/50 is probably preferable. It is nice to see a little bit of viscosity when cold, simply so that the oil can cling to some poorly lubricated surfaces such as the cam lobes.

 

I have never understood the idea that an old engine design should use an old type of oil - provided the machining tolerances are to modern standards I think you should use a modern oil. The difference when you strip an engine that has been running on synthetic is marked - clean components, less wear, no charred oil on the underside of the piston crowns etc.

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