For all things Rover V8, the TVR Griffith and Chimaera and TVR T-Cars
Oil
Synthetic or non-synthetic?
There is only one possible answer to the question: which is the better oil, synthetic or non-synthetic? The follow-up is always: why? There are many technical treatises on the web regarding motor oils but for those who want it straightforward and simple, here goes.
Lubricating oils have two major functions: lubrication and cooling. Whilst the two functions are not mutually exclusive the construction of an oil is to an extent a compromise between these two demands.
Mineral-based oils (from now on mineral oils) are basically refined. In other words, the manufacturers start with a base oil that contains many contaminants, particularly paraffins but lots of other materials as well, and these have to be removed as well as techniques and the target price allow. Whilst it is possible to remove them all, it is uneconomic to do so. Even when refined, mineral oils contain substances which are not required so have no particular function. Many of these can harm the engine.
Synthetic oils (from now on synthetics) are built up. In other words nothing is added which is not required. If it has no function it isn’t added.
The molecules in mineral oils vary in size. Once oil starts to flow then these different sized molecules will separate to an extent. The larger molecules will tend to adhere to the metal surfaces so providing a certain thermal barrier.
Given their different construction methods, the useful life of a mineral oil is considerably shorter than that of a synthetic. Even then the deterioration of mineral oils varies considerably depending on usage but this is not reflected in anything like the same manner in the more stable synthetics. 3000 mile change intervals for mineral oils is not merely a method for oil companies to boost profits. Many car manufacturers suggest 10,000 miles intervals with synthetics and this is by no means pushing the envelope.
I would appear to be clear that, despite the higher prices of synthetics, they do provide better value for money.
The main benefits of synthetics can be summarised as:
Less frequent oil changes
Better cooling
Less breakdown so less deposits and sludge
Better lubricating properties
Longer engine life
More efficient engine
And the downsides? Price is a possibility but is you take into consideration the savings with extended life of the engine, more efficient running giving better fuel consumption (or better performance if you prefer to take that) then there would seem there is little justification for any cost disadvantage.
So the answer to the question posed at the top of the article is: well, you can guess, can’t you?
Whilst there is a lot of truth in the suggestion that engineering excellence in manufacture has contributed enormously to the current remarkable reliability of modern engines, there is no argument that the engineering of oils has also played a major part. It is now the norm for engines to last 150,000 miles without problem and this despite the demands made on them with legislation and fuel consumption requirements. Further, no demands are made of the driver outside the service intervals, often a year apart.
But the Rover V8 is an engine from way back when and cannot be expected to perform without some regular monitoring. Speed 6 engines deserve the same as they are ‘specialist’ and highly tuned.
The handbook of RV8 and Speed 6 TVRs require the oil level to be checked on a weekly basis. However, many feel that it should be a daily task. I’m with this group. There is some suggestion that the oil level on Speed 6 cars is critical and a daily check is all but essential and it should be checked after a long run as well.
There is no overall ‘normal’ oil consumption as it varies from car to car. For a low mileage car used on a road, a litre of oil every 1000 miles is not excessive for an RV8 but I would do some checks if it dropped to half that. Speed 6 engines seem to be about as frugal. However, just because yours uses 10% more than the norm, or, worse still, your mate’s, it does not mean that you need a rebore. Oil consumption varies from engine to engine.
A highly tuned engine tends to use more oil than a standard one as tolerances tend to be bigger. For instance, piston and oil control rings will have a standard gap which, it is assumed, will close as the engine gets hotter, meaning that the piston will expand and the bore contract. Given the often greater ranges of temperature in tuned engines, this gap is often allowed to expand. Further, one way to limit friction losses is to have a looser fit of rings. This will, at times, allow oil up past the bores and into the combustion chamber and at other times allow any unburned fuel down into the sump.
Many engines, especially those tuned a little, are run on thinner oils. Instead of, say, a 10W/50, some go for a 5/40 or even a 0/40, the current Mobil 1 spec. This means that the oil, especially when cold, is much less viscous so with larger gaps the oil wanders around all over the place. So it can be seen that a drop in oil level does not necessarily mean you engine is dead and gone.
Two things you should note when checking the oil: its level and how quickly it has gone down. The first is quite simple. Get the car, with a warm engine, on a more or less level spot, let it rest for a while to allow the oil to drain from the more remote regions of the engine, and then check the level as described in the handbook.
The important bit is to make a note of the date and mileage any oil was added. A little bit of maths allows the mileage per litre to be worked out. Any significant increase in the short term must be investigated.
Consumption will vary on a day to day basis depending on how the car is driven. A cruise along the motorway for 100 miles means considerably less oil used than a drive of a similar
distance through a mix of A and B roads. Its all that lovely acceleration that does it. But even so, over the distance of 5-600 miles, it should more or less even itself out.
On the assumption that the level has dropped, you need to find out why. The most common reason is an oil leak. Whilst this is not particularly unusual, if significant it could stop you car being allowed on a track day. Whilst it is not too difficult discovering whether one has an external leak, the black film is a giveaway, the trick is finding out where the stuff is coming from.
If you keep you engine clean and oil-free then as soon as the first drip starts to ooze out onto the drive its source will be apparent. If you got to it a bit late and there’s a fair old mess then it is a case for a proprietary degreaser, like Gunk. Brush or spray it on, wash it off and then check it after every drive.
Some leaks can be ignored without too much worry. For instance, if there’s some seepage via a defective rocker cover gasket, then if it can be wiped after every drive then there is no worry as the oil is not under any great pressure. As long as it doesn’t get any worse it can be left until a convenient time. Somewhere like the sump, though, needs addressing fairly soon as such leaks can suddenly become much bigger and a sump without oil can be a bit of a pain. Check the leads to the oil cooler. These often vibrate with the engine revs and can foul parts of bodywork and engine bay. If they look a little dodgy then change them, and the jubilee clips as well.