I have never used 15w-40 in the D3 but did in the D1 & D2. I always used a mineral oil until this car.Quote:
Originally Posted by Learner
Cheers Ean
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I have never used 15w-40 in the D3 but did in the D1 & D2. I always used a mineral oil until this car.Quote:
Originally Posted by Learner
Cheers Ean
Quote:
Originally Posted by Learner
and further to what Ean said, the oils he's used in the past easily exceeded the spec called for in those engines.
A 15W-40 has reasonable pumpability down to around -15*C, a far lower temp than anything he'll ever see !
Question, is it possible that using oil with a higher viscosity could contribute to bearing shells moving due to drag when cold and the crank failures that have been suffered by a few 2.7 litre D3's?
Regards
Barryp
I've been using the DPF version Magnatec Professional C1 5W-30 in my 3.0 but will be using the A5 version from now on because of its reported better lubrication qualities than the C1 version and my 3.0 isn't fitted with a DPF. LR advise the use of a A1/B1 which has been superceded by A5/B5, not A3/B4 which has different characteristics although I don't know the specifics.Quote:
Originally Posted by ADMIRAL
LR issued a technical bulletin warning against using any different viscosity stating that it can lead to bearing failure.Quote:
Originally Posted by Barryp
Glad to hear that Graeme, that is why I stick to 5W-30.
The manufacturer has a good reason for the recommended viscosity.
Regards
Barryp
Perhaps not, but you were considering it. :eek:Quote:
Originally Posted by Ean Austral
Best Wishes,
Peter
Quote:
Originally Posted by Learner
Yep Peter you are correct, but decided that 5w-40 would be a better option .
Cheers Ean
Quote:
Originally Posted by Graeme
The specifics are A5/B5 requires a specific HTHS viscosity of >2.9 and <3.5. Otherwise the characteristics are extremely similar.
Castrol Edge Titanium 5/30 has HTHS visco of 3.5-3.6 so on or just outside of the higher rating, but it has what I'd consider a stronger additive package ie higher zinc/SAPS etc. And it is also based on a better Group IV full synthetic, where Magnatic is group III which is technically not a full synthetic at all. HTHS is important but it's not the be all end all. 2.9 cP is considered the minimum HTHS for any 30 weight oil.
But that's just my thought process and what works for me; I expect we're all using oil that suits how we drive, where we drive, how many cold starts, etc. If you're not doing a huge amount of cold starts then perhaps a 40 weight oil would work very well too, especially one like HPR5 which technically has a specification somewhere between a thicker 30 weight and a thinner 40 weight. I would not however use 5 50 under any circumstances in this particular engine - the design of the crankshaft and bearing configuration not having any tabs makes these engines particularly sensitive to wear, and the spec for 50 weight oil allows for the visco to be up to 115% thicker than 30 weight.
Remember the clearance between the crankshaft and the bearing shell is engineered so that the recommended oil can spread over the entire bearing surface before the piston reaches firing position which is nearly always before TDC. 50 weight leaves open the possibility that the oil will not spread quickly enough and therefore lead to wear on the bearing shell.
Quote:
Originally Posted by Rich84
That's not what actually happens though.
As soon as the crank starts to turn, a hydrodynamic wedge of oil forms and lifts the crank and bearing shell apart and the crank journal floats on this.
The pressure provided by the pump is there purely to prevent the oil wedge overheating by pushing the existing oil away and replenishing with nice, cool(er) oil.
I think what may be happening with these engines, and it's only a guess, I'm not familiar with them, is that the more viscous oil its creating too much drag between the shell and journal leading to the spun shell, (and then a lube failure as the oil feed hole has been 'lost') unlike a 'normal' spun bearing failure where the hydrodynamic and then boundary layer lubrication has broken down (oil breakdown, too much clearance, etc.) and that leads to a metal to metal situation.