darren m Posted August 1, 2014 Report Share Posted August 1, 2014 what is or is there a difference between multigrade and mineral oil i know all about the semi and syn but not the 2 above thanks Quote Link to comment Share on other sites More sharing options...
DaveyTed Posted August 1, 2014 Report Share Posted August 1, 2014 Traditionally oil were either mineral based or vegetable based. Very few oils now are vegetable based except classic car/motorbike oils. A mineral based oil can be multigrade like 0w30 for example or a single grade such as SAE30. Quote Link to comment Share on other sites More sharing options...
ditchman Posted August 1, 2014 Report Share Posted August 1, 2014 Thats how CASTROL started..making engine oil from the castor plant...castor oil...castrol !!....you can still get it for antique vehicles Quote Link to comment Share on other sites More sharing options...
neil82 Posted August 1, 2014 Report Share Posted August 1, 2014 speaking of Castrol, if your not sure which oil you need for your car try this http://oilselector.castrol.com/c/uk/eng/search Quote Link to comment Share on other sites More sharing options...
la bala Posted August 1, 2014 Report Share Posted August 1, 2014 Thats how CASTROL started..making engine oil from the castor plant...castor oil...castrol !!....you can still get it for antique vehicles And what wicked smell Castrol R has. Quote Link to comment Share on other sites More sharing options...
NickS Posted August 1, 2014 Report Share Posted August 1, 2014 Multigrade oil maintains its viscosity (how runny it is) over a much wider range of temperatures than "straight" oil. If you use a straight oil, it will be very runny in summer but thick as treacle in winter, making it hard to start the engine and to pump round the system. If you use a less viscous oil, it becomes too runny to maintain separation and coating of moving parts. A multigrade oil behaves like one of lower viscosity when cold but a higher viscosity one when hot. This makes starting easier, initial lubrication more effective and prevents excessing thinning when the engine is at normal running temperatures. So, a straight oil may be classed as "SAE 50" whereas a multigrade has two figures, for hot and cold, such as "SAE 5W 40" ie like a SAE 5 in the cold and SAE 40 when hot (the higher the number, the thicker the oil). SAE is just a standard unit to allow comparison. How it works.... Putting it simply, by adding long-chain molecules which curl up when cold and straighten out and get tangled up when hot, making the oil thicker. If you wish to be bored further, just ask! Nick Quote Link to comment Share on other sites More sharing options...
darren m Posted August 4, 2014 Author Report Share Posted August 4, 2014 Nick thats brill -- thanks Quote Link to comment Share on other sites More sharing options...
darren m Posted August 7, 2014 Author Report Share Posted August 7, 2014 another question -- if say the viscosity numbers are the same ie. 15w40 or 10w40, why are some oils labled for diesel and petrol and others just labeled for diesel if they,ve got the same numbers whats different between the two Quote Link to comment Share on other sites More sharing options...
keg Posted August 7, 2014 Report Share Posted August 7, 2014 One bit of bad news, in an idle moment, i looked at the history of the Castrol company and the founder was born a Lancastrian! Quote Link to comment Share on other sites More sharing options...
NickS Posted August 8, 2014 Report Share Posted August 8, 2014 Diesel engines operate at much higher peak pressures and temperatures in the combustion chamber. There are other performance standards for oil that cover the ability to withstand this without breaking down too quickly. Diesels also produce more acidic by-products which will cause corrosion if not neutralised. Even if not stated clearly, most lube oil intended for diesels also meet the standards for petrol engines as these are not as demanding. It doesn't make a lot of sense to use them, except for the sake of convenience, since they tend to be more expensive. Using the correct oil becomes even more important when the loads are higher. There was one class of ship in which the reduction gearboxes were wrecked whin somebody in procurement decided to save a few bob by buying cheaper lube oil that failed to stop the gear teeth pressure-welding themselves together at high power... I am not a fan of sealed gearboxes as I would rather be able to change the oil regularly. Nick Quote Link to comment Share on other sites More sharing options...
TriBsa Posted August 8, 2014 Report Share Posted August 8, 2014 And what wicked smell Castrol R has. Praise the sacred oil! Quote Link to comment Share on other sites More sharing options...
88b Posted August 8, 2014 Report Share Posted August 8, 2014 Very good explanation NickS , another difference is diesel oils tend to have a detergent content. Harley Davidson say to use diesel oil if you can't locate their own brand of banana skin and saw dust liquid sold at extortionate prices. As for changing transmission oil , most manuals now don't require it, more chance of the wrong oil being used. Same with wheel bearings. Quote Link to comment Share on other sites More sharing options...
NickS Posted August 8, 2014 Report Share Posted August 8, 2014 Early rotary engines used castor oil in a total loss oil system. The pilot would therefore be breathing a fine oil mist which, as Nanny would tell you, keeps you "regular"! "I say Caruthers, are you a Regular Officer?" "I should say so, Sir. I am commissioned into the Royal Flying Corps." Nick Quote Link to comment Share on other sites More sharing options...
amateur Posted August 9, 2014 Report Share Posted August 9, 2014 Early rotary engines used castor oil in a total loss oil system. The pilot would therefore be breathing a fine oil mist which, as Nanny would tell you, keeps you "regular"! "I say Caruthers, are you a Regular Officer?" "I should say so, Sir. I am commissioned into the Royal Flying Corps." Nick When I was at school, many, many years ago, one of the masters was an ex-RFC pilot, who swore that his fine shock of white hair was due to the regular mist of castor oil thrown out by his total-loss rotary engine. I must confess that I add a tea-spoon of R to the petrol tanks of both my classic bike and the lawnmower for that glorious scent. Quote Link to comment Share on other sites More sharing options...
oakland rob Posted August 10, 2014 Report Share Posted August 10, 2014 (edited) Diesel engines operate at much higher peak pressures and temperatures in the combustion chamber. There are other performance standards for oil that cover the ability to withstand this without breaking down too quickly. Diesels also produce more acidic by-products which will cause corrosion if not neutralised. Even if not stated clearly, most lube oil intended for diesels also meet the standards for petrol engines as these are not as demanding. It doesn't make a lot of sense to use them, except for the sake of convenience, since they tend to be more expensive. Using the correct oil becomes even more important when the loads are higher. There was one class of ship in which the reduction gearboxes were wrecked whin somebody in procurement decided to save a few bob by buying cheaper lube oil that failed to stop the gear teeth pressure-welding themselves together at high power... I am not a fan of sealed gearboxes as I would rather be able to change the oil regularly. Nick Diesel oil may meet the "Standard" for petrol engines but the same oil will perform differently in both engines as they both have different operating specs and have different lubricating requirements, Not sure what car/4x4 the op is talking about but 99% of the time a good quality mineral or semi synthetic of the right viscosity will do the job, Mineral oil is more than good enough in older engines as long as it is changed on a regular basis, ACEA and API Specs are what you should be looking at, Cant be bothered to go into in depth but have look here and it should answer all your questions - http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=8&cad=rja&uact=8&ved=0CFUQFjAH&url=http%3A%2F%2Fwww.carbibles.com%2Fengineoil_bible.html&ei=KonnU9zGNoed0QXyhYDwCA&usg=AFQjCNEdy8gCnkiTJWDtBVJ9qUGeeOSPKA&sig2=cCE7OnF_p49TqiSqqPEmrA&bvm=bv.72676100,d.d2k Edited August 10, 2014 by oakland rob Quote Link to comment Share on other sites More sharing options...
delburt0 Posted August 10, 2014 Report Share Posted August 10, 2014 (edited) Bit off post but... Don't read much into oil unless it's under warranty, or a really expensive car that will only go to the dealers. I've just bought some of halfords fully synthetic 5/30 for the wife's corsa, 1/2 price @ £12.00 for 5 ltrs for ford oil, Or £14.00 for vauxhall I bought ford. On the tin it says any petrol or diesal with 5/30 manufacturers reccomendations. Been in the game 25 yrs and never met a engine knowing the difference between vauxhall 5/30 and ford 5/30. This was not over models but the manufacturers. Just reccomendations they all do the same job just personnel preferences. Edited August 10, 2014 by delburt0 Quote Link to comment Share on other sites More sharing options...
oakland rob Posted August 10, 2014 Report Share Posted August 10, 2014 Bit off post but... Don't read much into oil unless it's under warranty, or a really expensive car that will only go to the dealers. I've just bought some of halfords fully synthetic 5/30 for the wife's corsa, 1/2 price @ £12.00 for 5 ltrs for ford oil, Or £14.00 for vauxhall I bought ford. On the tin it says any petrol or diesal with 5/30 manufacturers reccomendations. Been in the game 25 yrs and never met a engine knowing the difference between vauxhall 5/30 and ford 5/30. This was not over models but the manufacturers. Just reccomendations they all do the same job just personnel preferences. Not off post at all but with all due respect they don't all do the same job.! Different engines need different oil, With old (ish) engines if you use a Good Quality Mineral or Semi Synthetic Oil of the right spec then no probs, Use the same oil in a newer common rail diesel engine and see how you get on, Vauxhall and Ford do not make their own own oil, Mineral oil all comes from the same place, Its the base oil and refining process that makes the difference, A lot of oils that you put in your engine are "used oils" that have further been refined to be be suitable for internal combustion engines, A multigrade engine oil whether mineral or semi synthetic with the right SPECS will be fine for your engine. Quote Link to comment Share on other sites More sharing options...
delburt0 Posted August 10, 2014 Report Share Posted August 10, 2014 (edited) Not off post at all but with all due respect they don't all do the same job.! Different engines need different oil, With old (ish) engines if you use a Good Quality Mineral or Semi Synthetic Oil of the right spec then no probs, Use the same oil in a newer common rail diesel engine and see how you get on, Vauxhall and Ford do not make their own own oil, Mineral oil all comes from the same place, Its the base oil and refining process that makes the difference, A lot of oils that you put in your engine are "used oils" that have further been refined to be be suitable for internal combustion engines, A multigrade engine oil whether mineral or semi synthetic with the right SPECS will be fine for your engine.So what's the difference between vauxhall and ford fully synthetic 91>, the halfords parts manager couldn't answer it can you We are talking manufacturers not old or new cars (just after 91) and no stipulation on engine types either. But another spanner in the works both of the oils listed various manufacturers they advised the oil for use in over a full array of engines. Even though there both fully synthetic and both 5/30. Edited August 10, 2014 by delburt0 Quote Link to comment Share on other sites More sharing options...
steve_b_wales Posted August 10, 2014 Report Share Posted August 10, 2014 Speaking of engine oil. and changing the subject slightly (sorry) what are your thoughts of adding SLIK 50 to the engine? Quote Link to comment Share on other sites More sharing options...
delburt0 Posted August 10, 2014 Report Share Posted August 10, 2014 Speaking of engine oil. and changing the subject slightly (sorry) what are your thoughts of adding SLIK 50 to the engine? I no it invalidates your warranty Steve so can't be all well. Quote Link to comment Share on other sites More sharing options...
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