I have a 1998 Nissan almera 1.4 16v (GA14 engine). The owners manual suggests the use of 10w30 oil, however a friend has recommended 5w30 semi synthetic (says it is better on cold start, but same at normal operating temperature). The owners manual seems to show 5w30 with a very narrow operating temperature range.
Bottom line is it ok, and indeed beneficial to use the 5w30?
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What is the 'very narrow operating band'?? If you live in the South of England where the normal temperature range is -5 to +25 deg C and the oil fits in this band then no probs...
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I know it sounds odd, but the manual gives an operating range for 5w30 of -30 to +15, whereas 10w30 -20 to +40. What I can't get my head round is how can it be different at the higher temperatures if they both are 30 oils when hot. How does outside temperature have such an influence.
Ford zetec engines used to reccomend 10w30, but now reccomend 5w30 accross the board.
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Well, just to throw in some confusion, my book says that you should use 10w-40 semi-synthetic. Temp range for this -20 to +40 degC covers UK climate adequately.
You could use a fully synthetic 5w-40 but it's probably overkill to be honest.
Cheers
Simon
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Why do you want to go down to a 5w, although your friend says it helps with cold starting why change if you do not have a problem. a 5/6 year old car on 60K plus is not looking for thinner oil even at start up. A 10w40 Castrol Magnetec or similair is more than adequate. Regards Peter
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All the aforementioned oils will be satisfactory to do the job for you; it is really down to preference and how meticulous you want to be. 5w30 is the without doubt better on cold starts and will offer marginally better fuel economy especially on regular cold starts.
5w30 rated oils are generally API SL, which means that they offer excellent protection against thermal breakdown. A 10w30 probably will be API SJ, which is very good but not as efficient as the 5w30.
If it was my car and I was going to keep it for a while I would use bulk buy very cheap semi-synthetic 5w30.
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The rate at which the oil thermally breaks down will depend on the basestocks used. A cheap semi-synthetic will be a hydrocracked oil and it will break down quickly.
If you want an oil that is better for resisting thermal breakdown then the only option is an "expensive" fully synthetic which uses either poly alpha olefin or ester synthetic basestocks. These basestocks are far more thermally stable than petroleum ones.
I think you'll find that the shear tests for SJ and SL are the same.
Cheers
Simon
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The tests for API SL developed in 1999/2000 are somewhat revised compared to older API SJ. There is no doubt expensive fully synthetic is better for thermal breakdown protection. However not everyone wants to pay the best part of £40 for four litres of Mobil One, plus another £10 for the one litre product for topping up.
Semi synthetic (petroleum based blends) 5w30 is more than adequate for this vehicle and fully synthetic is a total overkill. Main dealer bulk 5w30 is high quality 'cheap' fuel economy oil for less than half the price of fully synthetics.
Fully synthetic is great for extended drain periods but a quality 5w30 semi synthetic changed every 6 months/5k miles will offer optimum protection.
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I can't argue with that I was just pointing out that cheap semi-synthetics are not the most thermally stable of oils.
There are two types of oil buyer - Price and Quality they do not go hand in hand I'm afraid.
There are many people that don't wish to change their oils every six months and for these people, synthetics are the better option as they are about twice the cost which in fact makes them no more expensive than semi-synthetics and with better quality ones you will get less wear and better protection for your money.
Different folks different strokes.
Cheers
Simon
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Thanks to all so far. I can source a quality COMMA 5w30 (API SL) for more or less the same price as 10w30 (API SJ), hence my interest in changing. The car has only done 34k from new and oil is changed every 5-6k without fail. If temperatures go above the range of 5w30 oil (mid summer?)what happens?
Can I therefore use 5w30 year round with confidence I am not doing any damage?
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My understanding (to be corrected as always) is that, while synthetic oil has better performance, its additive package still wears out like other oils, and therefore extended changes are inadvisable.
I am astonished at the prices you guys say you pay for Mobil 1. Where I live it is under GBP5 your money in a 1 ltr bottle in the local car supermarket, imported from Singapore as well, which means freight and duty included. Someone's getting ripped off, surely.
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You can get it for £5/litre in the UK (4l can for about £20) - if you know where to go.. ;-)
I think its about that price in France & Germany too. If you go to Halfords you get ripped - their prices for some branded oils are astonishing. They do sell their own-brand (rebranded Esso or Texaco?) fully-synthetic 5W-40 API SL for about £14.99 in 5l can, which I think is good value.
I can buy GM 'own-brand' fully-synth 5W-40 SL at about £50 for 25 litres, which is just £2/litre - they deliver it to my house too! Need to be trade customer to get that though.
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As a general rule of thumb.The type of oil you use is dependant on the type of engine(high performance or average) and the type of motoring you do (lots of cold starts,short trips etc or longer trips hammering up the motorway).I prefer 10w-40 for most applications but 5w-30 or 5w-40 for short stop/start urban driving.
A few years ago i asked a friend(senior oil chemist)at Mobil why their oil was so expensive in the uk.He told me;
1. That it is the best oil bar none,years ahead of other well known brands.
2. The cost is much higher in the uk,as most of the cost of mobil's advertising/sponsorship budget(F1 etc.)comes out of the uk.
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As a general rule of thumb.The type of oil you use is dependant on the type of engine(high performance or average) and the type of motoring you do (lots of cold starts,short trips etc or longer trips hammering up the motorway).I prefer 10w-40 for most applications but 5w-30 or 5w-40 for short stop/start urban driving.
Difference between 10W-40 and 5W-40 is only when the oil is cold. Once the engine is warm their viscosities will be v. similar. Its the 'hot' figure you need to worry about. The cold figure can be low as you want (0W, 5W) in winter - will help starting by the oil being a bit thinner. I've put 5W-40 in old high-mileage cars without a problem. Dropping to a 5W-30 would be another matter though.
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My 1.4 Almera ran very happily on Mobil 1, though, on reflection, it was overkill as I sold the car long before I'd have got any benefit from increased engine longevity.
Curiously, the Nissan's replacement, a Honda Accord 2 litre, didn't seem to like Mobil 1 at all (the engine was noticeably noisy when cold) and both the dealer and Honda themselves told me to switch to a good semi-synthetic 10w40, which I have done. Because this bothered me (how could a "lesser" oil work "better"?) I've researched the subject and come to the conclusion that unless you have an unusually stressed engine, or one that has been designed to run only on synthetic, most modern cars will do as well or even better using the aforementioned 'good semi-synthetic', in the manufacturer's recommended viscosity range, changed (along with the filter) every 5-6,000 miles.
On the whole, I can't think of any convincing reason why an Almera needs synthetic oil.
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At this source of expert opinion:
tinyurl.com/4dw2u
(a PDF file, so you'll need Acrobat Reader) you'll find the view that semi-synthetic oils are not worth the extra cost over good mineral oils. You'll also find an admitted bias in favour of top-grade synthetics, but there's a lot of good reasoning and some solid research underpinning it.
However, older cars accustomed to mineral oil shouldn't be given synthetic; there's plenty of evidence that it's not suitable. How old? Well, certainly anything more than 15 years old, and perhaps 10 would be a more appropriate limit, whatever mileage they've done.
This same source is emphatic that you get what you pay for, i.e. the higher prices of premium synthetic or mineral oils are justified for the superior products that they are.
I'm no technical expert and the views expressed here arise only out of extensive Web trawling and some hard evidence reported by others (e.g. the owner of an old car, the engine of which started leaking seriously 100 miles after being filled in error with synthetic).
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On the question of whether semi-synthetic oils are of any value over mineral equivalents (and with all due respect to the author of that work) who would you believe, him or Honda?
The Internet is a curious place, filled with all manner of authoritative sounding people with all manner of axes to grind.
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Here is a guy with no axe to grind as he's not a salesman.
At the end of the day it's your money and your choice!
I have John Rowlands permission to post this.
A word of caution ? You get what you pay for!
Below is an article written by John Rowland, Silkolene/Fuchs Chief R & D Chemist for 40 years.
Quote:
Costs of synthetics vary considerably. The most expensive are the ?Ester? types originally only used in jet engines. These cost 6 to 10 times more than high quality mineral oils.
The cheapest synthetics are not really synthetic at all, from a chemists point of view. These are in fact specially refined light viscosity mineral oils known as ?hydrocracked?. These have some advantages over equivalent mineral oils, particularly in lower viscosity motor oils such as 5w-30 or other oils with a low ?W? rating such as 5w-50 etc and they cost about 1.5 times more than good quality mineral fractions.
We use several different grades of this base oil, where appropriate. This is the ?synthetic? which is always used in cheap oils that are labelled ?synthetic?. Yes it?s a cruel world, you get what you pay for!
Now, you may ask, why are these special mineral oils called ?synthetic??
Well, it was all sorted in a legal battle that took place in the USA about ten years ago. Sound reasons (including evidence from a Nobel Prize winning chemist) were disregarded and the final ruling was that certain mineral bases that had undergone extra chemical treatments could be called ?synthetic?.
Needless to say, the marketing executives wet their knickers with pure delight! They realised that this meant, and still does, that the critical buzz-word ?synthetic? could be printed on a can of cheap oil provided that the contents included a few percent of ?hydrocracked? mineral oil, at a cost of quite literally a few pence.
So, the chemistry of ?synthetics? is complex and so is the politics!
The economics are very simple. If you like the look of a smart well-marketed can with ?synthetic? printed on it, fair enough, it will not cost you a lot; and now you know why this is the case. But, if you drive a high performance car, and you intend to keep it for several years, and maybe do the odd ?track day?, then you need a genuine Ester/PAO (Poly Alpha Olefin) synthetic oil.
This oil costs more money to buy, because it costs us a lot of money to make, very simply, you always get what you pay for!
Unquote:
Cheers
Simon
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I feel that we are all in agreement that premium fully synthetics are the best choice especially when it comes to thermal breakdown and extended drains. I also feel that semi-synthetic blends are superior to pure mineral oil especially when it comes to thermal breakdown and heat resistance.
A good example is that I did once own a Ford Fiesta with the hot running HCS engine, which is famous for causing mayonnaise type sludge when operated on mineral oil and used for short journeys.
I used good quality mineral oil but the sludge still persisted clogging up breather pipes etc. I then changed to a semi-synthetic (mineral based blend) and the problem was non-existent.
Semi-synthetics main weak spot as already stated previously is that it does lose its viscosity and is not suitable for extended drains. With interim oil changes between scheduled servicing it still offers superb protection.
Pure mineral oil is totally unsuitable for new modern multi valve engines however low viscosity semi synthetic blends are generally recommended by manufacturers.
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Well put sir!
Cheers
Simon
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If it were me then I'd use a 10w40 semi-synthetic & change the filter when I changed the oil every 5k miles (assuming this would be at least every 6 months).
I have a '95 Primera GT with the 2L 16v twin-cam engine and 160k miles under it's belt. For the past 50k miles I have done this (prior to this it got whatever Nelson fed it) and the engine just keeps on going...and going....and going....
10w40 semi 'Vauxhall' branded I can get for £12 from my local motor factor, and a fiver for an OEM oil filter. Doesn't use any oil between changes so after a couple of changes I have enough left over to just get a filter.
Hope that helps in some little small way...
cheers,
Stu
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