It is clear from all sorts of sources that the correct oil for Ford Zetec engines is 5W-30. To quote from another thread, "The wrong grade of oil in Zetec engines will cause the tappets to stick."
Do I take it that the key to this is the 5W and not the 30, so that flow is easier when the engine is cold? Or is the 30 equally important, such that 5W-40 would be bad for the engine, being thicker when hot?
And what about the possible effects of using 0W-30 and 0W-40?
The word "correct" notwithstanding, I'm interested in any other angles on this issue too.
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I myself always use 5W-30 as recommended by Mr Ford.
However, I know that a lot of garages put 5W-40 in because they don't keep 5W-30 in stock. Fast-Fit places are infamous for doing this.
I have heard of thicker oils causing problems with the hydraulic tappets but later Zetec engines don't have hydraulic tappets, so that shouldn't be a problem on a later engine.
Ford recommend 5W-30; why bother buying anything else?
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The other problem, particularly on the Sigma engines (1.25, 1.4, 1.6) Zetec units is that non-use of 5W/30 has been linked to premature cam bearing wear. The cam bearings are integral with the head, so any bearing problems require a complete replacement cylinder head.
As Galaxy says, Ford recommend 5W/30 and it's easy/cheap to buy so why risk anything else? These engines are bombproof if correctly serviced, so it's not worth the risk, IMO.
Cheers
DP
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IMO the 5W/40 will give more protection when hot, so will be no more likely to cause premature bearing wear than the 5W/30. Fords recommend the 5W/30 because it gives better fuel economy when hot. The Ford oil is a A1.B1. spec which is primarily for economy. The 5W is thin enough to circulate quickly when cold and thick enough to give adequate protection.
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I'd have to disagree. Protection is primarily a function of flow, not thickness (obviously this breaks down beyond a certain point) so 3W30 will be better than 5W40 under normal operating conditions.
I read somewhere that racing engines need a thicker oil as they run hotter. There was a great link in the technical section a while back about this.
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i have to disagree with Gordon m though. Not necessarily because he is wrong or not, but because oil is at best a compromise.
Firstly all oil viscosities are recommended by vehicle assemblers for a new engine; this may need to change with age/mileage. Their main consideration is sufficient lubrication with minimum drag (for fuel economy and easier starting). This is not necessarily good for the long life of the engine.
However in the case of this engine that does have specific problems with valves if wrong oil is used I would stick to grade recommended by the vehicle assembler/engine manufacturer.
A 3/30 (never heard of it or seen it personally)will get round the engine quickly at start up (subject to oil pump/oilways etc) but will not protect at cold as well as a 5/40. At hot the 5/40 will hold a little more in its body to again provide better protection. It is only the thickness of the oil that stops any 2 metal surfaces rubbing together, and within reason, the thicker that oil the greater the protection (generally).
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As my understanding of the sticky subject of oil stumbles forwards, I'm puzzled that you say that a 5/30 (presumably that's what was meant) "will not protect at cold as well as a 5/40". If the lower figure is the same, there's effectively no difference in cold-protection performance, is there?
In general, I thought that the lower the W figure (e.g. 5W, 10W)the better the oil circulates when cold, because of lower pour point (lower viscosity, better flow). The higher the second figure, the better it protects when hot, with anything over 40 being unnecessary for ordinary UK cars but relevant to high-performance engines run in hot ambient temperatures (e.g. racing in Saudi Arabia) or high-revving superbike engines used in the UK. The higher the second figure, the less readily it flows (i.e. it is more viscous) at full operating temperature; hence, some would advocate moving to a higher number as an engine ages and loosens up.
The logic of the 5W-30 choice for Zetec engines would appear to be that it is suitably thin when cold -- it flows more easily around the cold engine than a 10W-30 would -- and suitably thin when hot, flowing more easily than a 5W-40 would at the same temperature and therefore more certain to provide sufficient flow around the vulnerable components running hot.
But I could be wrong . . .
And just to throw another drop into the barrel, at
63.240.161.99/motoroil/101.html
you will find:
"It is time to dispel the notion that 0W-30 oil is too thin when our manual calls for 10W-30. A 0W-30 is always the better choice, always. The 0W-30 is not thinner. It is the same thickness as the 10W-30 at operating temperatures [i.e. the second number is the same in each case. RJ]. The difference is when you turn your engine off for the night [i.e. the first numbers are different. RJ]. Both oils thicken over the evening and night. They both had a thickness, a viscosity of 10, when you got home and turned your engine off. That was the perfect thickness for engine operation.
As cooling occurs and you wake up ready to go back to work the next day the oils have gotten too thick for your engine to lubricate properly. It is 75 F outside this morning. One oil thickened to a viscosity of say 90 [i.e. the 10W-30. RJ]. The other thickened to a viscosity of 40 [i.e. the 0W-30. RJ]. Both are too thick in the morning at startup. But 40 is better than 90. Your engine wants the oil to have a thickness of 10 to work properly. You are better off starting with the viscosity of 40 than the honey-like oil with a viscosity of 90.
I repeat: More confusion occurs because people think in terms of the oil thinning when it gets hot. They think this thinning with heat is the problem with motor oil. It would be more correct to think that oil thickens when it cools to room temperature and THIS is the problem. In fact this is the problem. [bold added by RJ]"
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good post, good material.
But I believe he meant 0/30 but put 3/30 versus 5/30.
In a new engine 0/30 is better if it specified for that engine. But in an older engine or 1 that it is not specified for, then 5/30 is better.
IMO
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