garetheves Posted May 9, 2005 Share Posted May 9, 2005 I know there are loads of threads on this topic but unfortunately im in a rush and dont have time to check, hoping someones on that can give me a quick response. I have a 94 TT 6spd J-spec running fully decat, will the above "hypergrade" oil be ok?? Cheers Link to comment Share on other sites More sharing options...
carl0s Posted May 9, 2005 Share Posted May 9, 2005 i reckon something more along the lines of 5w/40 would be better but I could be wrong. Link to comment Share on other sites More sharing options...
Alex Posted May 9, 2005 Share Posted May 9, 2005 15w40 will be ok in the summer...just make sure it's good quality, and Fully Synthetic. I personally use Silkolene Pro S 10w50 from Opie Oils Link to comment Share on other sites More sharing options...
garetheves Posted May 9, 2005 Author Share Posted May 9, 2005 Cool cheers for th replies guys. Link to comment Share on other sites More sharing options...
oilman Posted May 13, 2005 Share Posted May 13, 2005 Is this Duckhams Hypergrade? Oh no, it's a mineral oil. Just not good enough IMHO. Use Fully synthetic and a proper one at that. Cheers Simon Link to comment Share on other sites More sharing options...
JohnA Posted May 13, 2005 Share Posted May 13, 2005 i reckon something more along the lines of 5w/40 would be better but I could be wrong. Aye, with mr "T" recommending SAE30 ---> SAE40max I wouldn't want anything thicker. The number of posts in the US forum regarding blown crank seals makes me wonder if high oil viscosity plays a part... Link to comment Share on other sites More sharing options...
oilman Posted May 13, 2005 Share Posted May 13, 2005 I wouldn't use higher than a 10w-50 unless it's a dedicated track car then 15w-50 may be an option. 5w-40, 10w-40 or 10w-50 (for highly modded or track use or if you are seeing oil temps in excess of 120degC) would be my recommendations. Cheers Simon Link to comment Share on other sites More sharing options...
SUPRALOOPY Posted May 13, 2005 Share Posted May 13, 2005 i use mobil 1 is this ok for j spec cars??????? as i am now after a couple of days getting blue smoke at startup and then nothing after that??? is valve stem oil seals or something worse?????????? Link to comment Share on other sites More sharing options...
oilman Posted May 13, 2005 Share Posted May 13, 2005 Which Mobil 1? 0w-40 or 15w-50 Cheers Simon Link to comment Share on other sites More sharing options...
SUPRALOOPY Posted May 14, 2005 Share Posted May 14, 2005 0w-40 as i thought this was the best oil you can get Link to comment Share on other sites More sharing options...
carl0s Posted May 14, 2005 Share Posted May 14, 2005 I read on here that the 0w Mobil-1 was too thin for some of the seals on the Supra. Link to comment Share on other sites More sharing options...
JohnA Posted May 14, 2005 Share Posted May 14, 2005 If the manufacturer specifies 10w30 or 10w40, I'd think hard before moving to a thicker one, especially with an engine known for oil pressure issues (although it might have been inadequate crank ventilation in some cases of failed seals) Link to comment Share on other sites More sharing options...
Alex Posted May 14, 2005 Share Posted May 14, 2005 0w40 is too thin. It will get passed the seals. I'd swap it out. 5w is as thin as you should go...and only in the winter or if you make mostly short journey's Link to comment Share on other sites More sharing options...
SUPRALOOPY Posted May 14, 2005 Share Posted May 14, 2005 cheers...its comig out then! that was a waste of money but what is a very good oil to replace it with?????? Link to comment Share on other sites More sharing options...
JohnA Posted May 14, 2005 Share Posted May 14, 2005 It's a public forum mate, and you'll get varied opinions, that's how it works. If it were my car, I would keep the 0w40, I had been using it for years on turbos, despite everyone saying 'it's too thin' etc. I found it very good indeed, and changing into 15w50 made no difference whatsoever into the amount of smoke from a worn turbo bearing (I've been through a few in the past) Changing the piston rings, makes a difference, yes. Reconditioning the turbo, also makes a difference (not always positive, lol...) But simply changing to 'thicker' oil I've never seen it make any difference --- and yes, I've tried it, as it appears to be a 'quick fix' Others claim to have moved on to 'thicker oil' and all their smoking problems were solved. What can I say? It's a free country... Link to comment Share on other sites More sharing options...
oilman Posted May 14, 2005 Share Posted May 14, 2005 Ok, people need to get their heads around this and I will try to explain it without getting over technical and we'll go from there. 0w-40, 5w-40, 10w-40 and 15w-40 are all the same thickness (14cst) at 100degC. Centistokes (cst) is the measure of a fluid's resistance to flow (viscosity). It is calculated in terms of the time required for a standard quantity of fluid at a certain temperature to flow through a standard orifice. The higher the value, the more viscous the fluid. As viscosity varies with temperature, the value is meaningless unless accompanied by the temperature at which it is measured. In the case of oils, viscosity is generally reported in centistokes (cst) and usually measured at 40degC and 100degC. So, all oils that end in 40 (sae 40) are around 14cst thickness at 100degC. This applies to all oils that end in the same number, all oils that end in 50 (sae 50) are around 18.5cst at 100degC and all oils that end in 60 (sae 60) are around 24cst at 100degC. With me so far? Great! Now, ALL oils are thicker when cold. You're confused! It's true believe me and here is a table to illustrate this. SAE 40 Temp degC.........................Viscosity (thickness) 0..........................................2579cst 20..........................................473cst 40..........................................135cst 60..........................................52.2cst 100........................................ 14cst 120.........................................8.8cst As you will see, there is penty of viscosity at 0degC, in fact many times more than at 100degC and this is the problem especially in cold weather, can the oil flow quick enough to protect vital engine parts at start up. Not really! So, given that an sae 40 is 14cst at 100degC which is adequate viscosity to protect the engine, and much thicker when cold, how can a 0w oil be too thin? Well, it can't is the truth. The clever part (thanks to synthetics) is that thin base oils can be used so that start up viscosity (on say a 5w-40 at 0degC) is reduced to around 800cst and this obviously gives much better flow than a monograde sae 40 (2579cst as quoted above). So, how does this happen, well as explained at the beginning, it's all about temperature, yes a thin base oil is still thicker when cold than at 100degC but the clever stuff (due to synthetics again) is that the chemists are able to build these oils out of molecules that do not thin to less than 14cst at 100degC! What are the parameters for our recommendations? Well, we always talk about good cold start protection, by this we mean flow so a 5w will flow better than a 10w and so on. This is why we recommend 5w or 10w as the thickest you want to use except in exceptional circumstances. Flow is critical to protect the engine from wear! We also talk about oil temps, mods and what the car is used for. This is related to the second number xw-(XX) as there may be issues with oil temperatures causing the oil to be too thin and therefore the possibility of metal to metal contact. This is difficult to explain but, if for example your oil temp does not exceed 120degC at any time then a good "shear stable" sae 40 is perfectly capable of giving protection. "Shear stability" is important here because if the oil shears it thins and that's not good! However, if you are seeing temperatures in excess of 120degC due to mods and track use etc then there is a strong argument to using an sae 50 as it will have more viscosity at these excessive temperatures. There are trade offs here. Thicker oils cause more friction and therefore more heat and they waste power and affect fuel consumption so it's always best to use the thinnest oil (i.e. second number) that you can get away with and still maintain oil pressure. There is more but this post is too long already so lets keep it to basics. Cheers Simon Link to comment Share on other sites More sharing options...
JohnA Posted May 14, 2005 Share Posted May 14, 2005 ...So, given that an sae 40 is 14cst at 100degC which is adequate viscosity to protect the engine, and much thicker when cold, how can a 0w oil be too thin? Well, it can't is the truth. ...This is difficult to explain but, if for example your oil temp does not exceed 120degC at any time then a good "shear stable" sae 40 is perfectly capable of giving protection... Very true. At last someone else can see behind this "0w40 is too thin" malarky. How can it be too thin? In the icy winter it flows better than the others on startup, and at operating temps it's SAE40, as per manufacturer's recommendation. If anything, synthetics like Mobil1 retain their viscosity for longer under extreme temps, before they become like running water. Mr "T" is quite clear about viscosities, and nothing over SAE40 is in the manuals. In fact even 10w30 covers the British climate. Link to comment Share on other sites More sharing options...
oilman Posted May 14, 2005 Share Posted May 14, 2005 Indeed but there are other factors. Lower than 5w is fairly overkill in our climate that's why we recommend 5w and 10w. The wider the viscosity range the more prone to shear as more VI Improvers are required which leads to more rapid thinning and 5w-40 is narrower than 0w-40. Other than these factors which make 5w-40 a better bet for UK climate and shear stability, yes it's a darn site better than 10w-60! Cheers Simon Link to comment Share on other sites More sharing options...
normore1 Posted May 14, 2005 Share Posted May 14, 2005 Finally someone who understands the thick and thin (excuse the pun) of multi-viscosity oils. Excellent technical data that dispels all the BS and popular misconceptions of the "..I heard somewhere" and "... I read somewhere" ancedotes. General recommendation for the Supra is: go with a quality synthetic oil with the lowest possible cold start viscosity and a moderate viscosity spread. Synthetic 5W-30 is a good choice. 0W-40 5W-40 and 15W-50 weight oils can have high concentration of viscsity modifiers (not 100% true with synthetics) and can be a little heavy at high temperature which can rob power. BTW, avoid hydro-cracked oils (Castrol Syntec) which are better than regular dino oil but not true synthetics. The low temp flowability, temperature stability and flash point specs are not even close to a true ester/PAO synthetic. Link to comment Share on other sites More sharing options...
garetheves Posted May 15, 2005 Author Share Posted May 15, 2005 so basically im best staying with the 10w-30 that it says on the side of the engine? or 10w-40? Link to comment Share on other sites More sharing options...
oilman Posted May 15, 2005 Share Posted May 15, 2005 Yes, sort of. If it says sae 30 or sae 40, unless the car is modded or used on track you can use a 10w-30 or a 10w-40 but better still would be 5w-30 or 5w-40, you could even use 0w-30 or 0w-40. Cheers Simon Link to comment Share on other sites More sharing options...
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