mkII 1.8 'tappetty'
Discussion
don't know about bikes. F1 would be i guess a 20 or equivalent of something a little bit skinnier depending on how much the engine guys like to push it - certainly the cosworth engine in the williams used a 20. they also sold a 0W-20 that was advertised as being their F1 oil but i don't reckon it was, not much point in having a multigrade in F1...
I appreciate the reply, thank you. I apologise for comments made and I realise you were trying to bring home a point.
It seems that a lot of oil companies list a 5w/30 semi synthetic for the MX5 from 1989 onwards, Comma, Millers, Carlube etc. Castrol funny enough list a 10w/40 for the 1.6, 1.8 but the turbo model from 1990 onwards Castrol list a 5w/30 fully synthetic.
I know things are changing regards fuel economy and emissions but the /30 grade has good film strength and I believe will more than do the job. As you have shown the /grade is coming down as Moto GP and formula 1 have demonstrated and I believe they use a Mono grade oil, Ford are working on a road car engine design at present with a 5w/20 or 0w/20 oil in mind.
As most on this forum use there cars every day with occasional fast road use a 5w/30 fully synthetic oil will more than meet there requirements.
I do agree with you that under different circumstances such as track use where greater heat build up occurs a step up to a /40 grade would help with the extra stress on the engine over the sacrifice of a few BHP and less fuel economy.
noisy tappets
Mobil 1 0w/40 fully synthetic is one of the best and a good all round choice, when changing the oil you bennifit from a fresh oil and the additives pack helps to clean the varnishing from the moving parts helping with lubrication and heat dissipation freeing up movement and taking away the noise, as described, the older the oil the more potential for deposits to be left and the problem returning. Use the best oil you can afford and stick to the recommended service intervals or less. If you use the car on track you increase the amount of unburnt fuel, moisture, sulphur etc passing the cylinder ending up in the sump, the oil has to deal with this so it is advisable again to change the oil on a more regular basis. After you complete your laps it is worth letting the engine tick over for a few minutes letting the oil circulate to take away the heat and let the engine cool correctly to avoid burning the oil.
It seems that a lot of oil companies list a 5w/30 semi synthetic for the MX5 from 1989 onwards, Comma, Millers, Carlube etc. Castrol funny enough list a 10w/40 for the 1.6, 1.8 but the turbo model from 1990 onwards Castrol list a 5w/30 fully synthetic.
I know things are changing regards fuel economy and emissions but the /30 grade has good film strength and I believe will more than do the job. As you have shown the /grade is coming down as Moto GP and formula 1 have demonstrated and I believe they use a Mono grade oil, Ford are working on a road car engine design at present with a 5w/20 or 0w/20 oil in mind.
As most on this forum use there cars every day with occasional fast road use a 5w/30 fully synthetic oil will more than meet there requirements.
I do agree with you that under different circumstances such as track use where greater heat build up occurs a step up to a /40 grade would help with the extra stress on the engine over the sacrifice of a few BHP and less fuel economy.
noisy tappets
Mobil 1 0w/40 fully synthetic is one of the best and a good all round choice, when changing the oil you bennifit from a fresh oil and the additives pack helps to clean the varnishing from the moving parts helping with lubrication and heat dissipation freeing up movement and taking away the noise, as described, the older the oil the more potential for deposits to be left and the problem returning. Use the best oil you can afford and stick to the recommended service intervals or less. If you use the car on track you increase the amount of unburnt fuel, moisture, sulphur etc passing the cylinder ending up in the sump, the oil has to deal with this so it is advisable again to change the oil on a more regular basis. After you complete your laps it is worth letting the engine tick over for a few minutes letting the oil circulate to take away the heat and let the engine cool correctly to avoid burning the oil.
no worries 
if it was *just* about the viscosity, then a 5W-30 would be fine for 95% of applications, but it's just the hit of the low HTHS (high temp high shear) property of the FE oils that to me makes them unsuitable. the non FE 5W-30's would be fine.
as for specs, to be honest sometimes it's a bit hit and miss. for example the ford specs - in all the databases now, all fords are listed as being ok on a 5W-30 FE oil - they have retrospectively applied it across the whole range, so that if you get a recommendation for an old capri or cortina, the database will bring up a 5W-30 initially, even tho a 10W-40 or 10W-50 would be more suitable. with the mazda / ford tie up, they may have retrospectively applied a 5W-30 FE recommendation to some cars that weren't designed for it.
i think most new honda's now take a 0W-20 FE oil - but they are designed to take it.
especially on track when you're getting higher bulk oil temps, where the oil will thin down further than under normal road use, i think it's always worth using a thicker grade of oil
i don't know about the procedure on motoGP but in F1 they don't generally use VII improvers to give better hot *and* cold performance because there is no cold temperature running - the engines are heated, oil is heated and water heated before the engines can be started. the problem with using VII improvers is that they can shear with mechanical action and so the oil loses high temp viscosity permanently, whereas getting the viscosity from the base oil means that it will keep it's viscosity better. you are pushing for every last BHP, the oils are very different to road car engine oils (i.e. they don't generally contain detergent / dispersant as these components are surface active and so replace friction modifier / anti-wear chemistry), as well as having a very skinny oil they push the temps to around 150 degrees C, and an engine won't go more than a day without an oil change so i don't really think that road cars are taking from F1 especially strongly in that regard. yes skinny oils do give more power but for most manufacturers, FE is more important than power, and for high power cars the oils are almost always thick oils to give protection under hard conditions - ferrari's, lambo's, BMW M-series etc all take either a 5W-50 / 10W-50 or 10W-60
if it was *just* about the viscosity, then a 5W-30 would be fine for 95% of applications, but it's just the hit of the low HTHS (high temp high shear) property of the FE oils that to me makes them unsuitable. the non FE 5W-30's would be fine.
as for specs, to be honest sometimes it's a bit hit and miss. for example the ford specs - in all the databases now, all fords are listed as being ok on a 5W-30 FE oil - they have retrospectively applied it across the whole range, so that if you get a recommendation for an old capri or cortina, the database will bring up a 5W-30 initially, even tho a 10W-40 or 10W-50 would be more suitable. with the mazda / ford tie up, they may have retrospectively applied a 5W-30 FE recommendation to some cars that weren't designed for it.
i think most new honda's now take a 0W-20 FE oil - but they are designed to take it.
especially on track when you're getting higher bulk oil temps, where the oil will thin down further than under normal road use, i think it's always worth using a thicker grade of oil
i don't know about the procedure on motoGP but in F1 they don't generally use VII improvers to give better hot *and* cold performance because there is no cold temperature running - the engines are heated, oil is heated and water heated before the engines can be started. the problem with using VII improvers is that they can shear with mechanical action and so the oil loses high temp viscosity permanently, whereas getting the viscosity from the base oil means that it will keep it's viscosity better. you are pushing for every last BHP, the oils are very different to road car engine oils (i.e. they don't generally contain detergent / dispersant as these components are surface active and so replace friction modifier / anti-wear chemistry), as well as having a very skinny oil they push the temps to around 150 degrees C, and an engine won't go more than a day without an oil change so i don't really think that road cars are taking from F1 especially strongly in that regard. yes skinny oils do give more power but for most manufacturers, FE is more important than power, and for high power cars the oils are almost always thick oils to give protection under hard conditions - ferrari's, lambo's, BMW M-series etc all take either a 5W-50 / 10W-50 or 10W-60
Gassing Station | Mazda MX5/Roadster/Miata | Top of Page | What's New | My Stuff