oilman Posted April 5, 2006 Share Posted April 5, 2006 A short lesson on Multigrades: If you see an expression such as 10W-40, the oil is a multigrade. This simply means that the oil falls into 2 viscosity grades, in this case 10W & 40. This is made possible by the inclusion of a polymer, a component which slows down the rate of thinning as the oil warms up and slows down the rate of thickening as the oil cools down. It was first developed some 50 years ago to avoid the routine of using a thinner oil in winter and a thicker oil in summer. For a 10w-40 to attain the specification target a 10W ( W = winter) the oil must have a certain maximum viscosity at low temperature. The actual viscosity and the temperature vary with the viscosity grade but in all cases the lower the number, the thinner the oil, e.g. a 5W oil is thinner than a 10W oil at temperatures encountered in UK winter conditions. This is important because a thinner oil will circulate faster on cold start, affording better engine protection. For a 10w-40 to attain the other specification target a 40 oil must fall within certain limits at 100 degC. In this case the temperature target does not vary with the viscosity grade, if there is no "W", the measuring temperature is always 100degC. Again the lower the number the thinner the oil, a 30 oil is thinner than a 40 oil at 100 degC., which is typical of maximum bulk oil temperatures in an operating engine. The engine makers are, of course, very well aware of this and specify oils according to engine design features, oil pump capacities, manufacturing tolerances, ambient temperature conditions etc. It is important to follow these guidelines, they are important and are an are stipulated for good reasons. If the engine has been modified, the operating conditions may well be outside the original design envelope. The stress on the oil caused by increased maximum revs, power output and temperature may indicate that oil of a different type and viscosity grade would be beneficial. Cheers Simon Quote Link to comment Share on other sites More sharing options...
Chesterfield Posted April 5, 2006 Share Posted April 5, 2006 You certainly know your oil! Thats some good info. I suppose thats why my oil pressure is quite high if the revs go over 3500 inside the first few minutes of driving - i.e. before it warms up thoroughly, Once its warm, the pressure gauge does not regsiter as high during acceleration. Quote Link to comment Share on other sites More sharing options...
Liam's Z Posted April 5, 2006 Share Posted April 5, 2006 Simon in your professional opinion, what grade/make oil would you recommend for a standard 350z, As opposed to a 350z with a induction kit fitted??? Cheers Liam. Quote Link to comment Share on other sites More sharing options...
Removed Posted April 5, 2006 Share Posted April 5, 2006 I think it is the consensus that the 5W40 is the best grade for the Z I personally quite like the Motul 300V as fully synth. wouldn't see the need for a different oil just because there's an induction kit fitted as the modification is so minimal I don't think it would make a difference Quote Link to comment Share on other sites More sharing options...
oilman Posted April 5, 2006 Author Share Posted April 5, 2006 Hi, Still go for a 5w-40 full synthetic as the top option. Regards Simon. Quote Link to comment Share on other sites More sharing options...
Liam's Z Posted April 5, 2006 Share Posted April 5, 2006 Hi, Still go for a 5w-40 full synthetic as the top option. Regards Simon. Nice one Simon, that's exactly what she's got... Even though the dealer wanted 2 poor semi 10w-40 down her throat Quote Link to comment Share on other sites More sharing options...
Jacko Posted April 5, 2006 Share Posted April 5, 2006 Good info this..... can we get it in Technical as well as makes a lot of sense being in there? Quote Link to comment Share on other sites More sharing options...
Chesterfield Posted April 5, 2006 Share Posted April 5, 2006 Good idea! Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted April 5, 2006 Share Posted April 5, 2006 You mean add it to this one http://www.350z-uk.com/forum/viewtopic.php?t=54 Quote Link to comment Share on other sites More sharing options...
l33r0y Posted April 5, 2006 Share Posted April 5, 2006 Hi, Still go for a 5w-40 full synthetic as the top option. Regards Simon. I've heard that semi-synth was the choice for the first oil change (while the engine is running in) then afterwards its fine to go fully synth. Is there any truth in this? L. Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted April 5, 2006 Share Posted April 5, 2006 Most people go mineral (not semi-synth) until first service Quote Link to comment Share on other sites More sharing options...
Gus Posted April 5, 2006 Share Posted April 5, 2006 The first official oil change is 9000 - it is OK to go fully synth at this mileage. Some people will go for an additional early change at 1500, or 2000 or 3000 - it was previously recommended to go semi-synth at this point Gus Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted April 5, 2006 Share Posted April 5, 2006 The car is delivered with mineral (well the old versions were) - if you do carry out an intermediate change to semi-synth (which I would agree is fine to do), you could potentially void your warranty - well, you might have to argue the point at the very least Quote Link to comment Share on other sites More sharing options...
Winged Rodent Posted April 6, 2006 Share Posted April 6, 2006 - if you do carry out an intermediate change to semi-synth (which I would agree is fine to do), you could potentially void your warranty - well, you might have to argue the point at the very least Nowhere in the manual does it state 'Do not use synthetic oil' or 'Only use mineral oil.' Nissan would be on very shaky ground if they tried to deny an engine warranty claim solely because of using synthetic oil - Provided it met the specifications defined in the manual. However, they would have more grounds to deny a warranty claim if you used 5W-40 (synth or mineral) as nowhere in the manual does it list this as a recommended or approved grade (I know it doesn't say don't use it either). I know that is unlikely as a '5W' spec is approved in the manual as a 5W-30 and the '40' spec as a 10W-40 - the 5W-40 just has a wider viscosity spread. And, FWIW, I've been running full synth in my 350Z since 4.5k with no problems what so ever. Quote Link to comment Share on other sites More sharing options...
Guest prescience Posted April 6, 2006 Share Posted April 6, 2006 I was playing Devil's Advocate I was expecting Simon to chime in himself as I recall he did this in the past Felt it was just worth making the point though, so people are clear; ta for that Quote Link to comment Share on other sites More sharing options...
l33r0y Posted April 6, 2006 Share Posted April 6, 2006 Do Nissan have a policy with what they use, or is it dependant on an individual service centre policy? Probably getting the oil from Oilman will be cheaper and at least you'll know what it going in... Quote Link to comment Share on other sites More sharing options...
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