I wondered whether anyone could advise on what might be expected as a reasonable oil consumption figure for an AV590 and how this might compare with a more modern Cummins or Iveco type.

I've heard many conflicting opinions on the subject. An ex Eastbourne corporation foreman once told me that - in the time when they had Regent V's (with AV590's) and PD2's (with Leyland 0.600's) they would change the engine if a bus consumed more than 3 pints a day. since the daily mileage was only about 70-100 this seems very high!

My bus number (if any): RM1699 Eastbourne Regent V 69

That's a question that probably cannot be answered.

When I was at HL, several buses in the 27XX were monitored from new and then compared with the Merlins that arrived shortly after.
I seem to remember that three different oil types were used, but as the youngster, I was not in on the survey.
The consumption was about parrallel for about 4 months then the Merlins took to drink - with the foreman needing to join them!!
I was led to understand that the then new RMLs were using at best about a pint every 2 months, but it varied from bus to bus. Trouble is the way it was measured was far from accurate with no gauges and sealed fillers. So it could not be relied on that another shift had done a top up. HL was too busy and many too wrapped up in union politics to actually care about pride in their job.
A hangover from trolleybus days that never lifted till closure.
What we did find is more damage came from overfilling and this is what dogged the Merlins, It was so much easier on an RM to do a visual check and fill if required.

Then of course, engines just went off to Chiswick and lord knows how often some of those lumps were overhauled.
As they all came fully tagged, corresponding records must have existed and that the works and research lot must have compiled a whole lot of stats.

Presumably this is all in the hands of the LT museum.

Now, you would need a brand new AEC unit, a fully rebuilt unit and a worn but serviceable unit to make a comparison.

But it would be interesting to see a modern day result with modern oils and fuels.

High oil consumption is certainly an indicator of a wearing engine as is black smoke! Both those engines in LT buses always burned some oil and it was quite common for them to leak around the sump so the oil was regularly topped up on the run in, two pints a day was not at all unusual. AS a note, its important to keep the air intake clean on an RM otherwise there is back pressure and the engine throws oil out, but RMs always used more oil than the RT family buses.

Three pints a day is maybe a bit over the LT norm but would not in itself be an indicator of the need for an engine change. The oil put in a bus on the run in was recorded in theory but was by no means accurately measured except on rotas, but exessive oil use was a contributor as well as date fitted, lack of power, obvious leaks and disturbing noises, as to whether an engine needed changing. We often put in a litre or so of oil before starting out in the morning in our RTs but they can do quite high mileage and have 40-year-old engines which do smoke a bit on hills!!

My bus number (if any): RTL 960, RML 2667, RM 1585, RMC 1458 and 14 RTs

This is something that probably wouldn`t have gone down too well among LT engineering bosses in the 1980`s, but those who recall RM 1563 at Mortlake would possibly also recall that it had an exceptionally quiet Leyland engine. It wasn`t that it was noisey before Neil T and I started `looking after it`, more a case of a very tidy silver sprayed and pipe polished engine looking messy due to persistant oil leaks. We wanted it to look spotless!

Neil T had long been unhappy at the quality of LT spec engine oil which, when drained, came out with such little viscosity as to be quite lamentable. His solution? To buy, from his own pocket, something much more substantial in the hope that 1563 would benefit from it. I can`t remember what he got but it came from the BP garage between Hogarth Roundabout and Hammersmithg flyover. It was brilliant. Visibly much thicker, the engine was immediately significantly quieter and the bus became a dream to drive - totally different from other Leylands. A fact that many reading this will probably remember. And no oil leaks to spoil the appearnce under the bonnet.

Being a small shed with some really good blokes working there it was fairly easy to get the co-operation of those on the `run in` to not put standard oil in it. In any case when they dipped the oil it never showed signs of needing any. I know it was very expensive back in 1981 /2 and I rather suspect that Neil T didn`t actually let on as to how much it was costing him to do this but I can tell you that it made one hell of a difference.

Going on a couple of years, I restored DMS 1 for the LT museum. After six months work it was FFD`d and ready for the road. Its first major outing was to a rally in Birmingham - a rather ambitious trip for a DMS that hadn`t been any distance in years. It performed faultlessly but when we got back to Stamford Brook (where it lived) we were dismayed when we lifted the bonnet to find the engine splattered with this `weak tea` LT spec oil. It had ruined the silver spray appearance, all the clean pipework and hours of our time in doing this. We knew exactly what needed to be done. A visit to the BP garage and, this time out of my pocket, we came back with whatever this stuff was. Drained the old oil out, refilled, steam cleaned the engine bay then repainted and polished where required. Couldn`t wait for the following weekend and another long trip to a rally which I think was at the Science Museum store at Wroughton. All those miles at speed on the M4 and not an oil leak or dribble anywhere as a result and nor on any other trip thereafter for as long as I remained associated with the bus. And again the engine ran much quieter.

So, there`s the proof of getting what you pay for. Not that I would suggest that any bus owner should rush out and buy the best oil on the shelf. Neil T was quite mindful of the consequences of `getting it wrong`. He wrote to several major oil companies and perused many brochures that were sent to him before that first filling and did it only once he was sure it wouldn`t all end in tears. It did eventually become common knowledge that 1563 had something different in its engine and several of us having seen the benefits of it would really have liked an active experiment using perhaps half of our fleet at Mortlake to see if an eventual cost saving could be achieved by using so much less of the more expensive alternative. But the possibility of us being stopped from having the enjoyment we did with 1563 was enough incentive to just keep our heads down!

I recall RM1563 and it's legendary ' Rolls-Royce Leyland' that purred and gurgled like no other.
I also vaguely recall the oil being BP Vanellin 3C or something like that. I think NT told me that along with his theory of LT owning a tanker called the Dextron Princess purely for the thirst of Metrobuses!

Jack, you`ve jogged my memory! It was Vanellus C3 oil. And as for Dextron - a standing joke about LT having shares in the stuff. I suspect you had as many pink trails around the floor at HL as we did at V. Many an `in garage` slide was caused by that stuff leaking out of Metrobuses.

I hadn't expected a definitive answer to my original question, but the responses have nevertheless been very revelaing and informative.

I've found that oil consumption in my 2 buses (both AV590's) average out about 1 pint/250 miles, not as good as the Hanwell RML's, but not bad given the engines are around 45 years old.

As I've mentioned previously on this forum, both engines were stripped and completely overhauled (rings replaced although not the liners) and therefore should in theory be in fairly good condition.

It's interesting that the smoke from the RM exhaust in minimal (except of course when starting from cold) whereas emissions from the Regent V always seem to be more noticable. I'm wondering whether this may be due to the fact the the engine on the RM is de-rated (although I'm not sure about the Regent). I gather this was done to reduce emissions and to prolong the engine life.

Whilst the maximum speed of both vehicles is 42mph, the Regent is far more sprightly than the RM. I'm not sure whether this is due to the engine on the RM being derated or due to the fact that the Regent has a manual box that makes the vehicle more responsive than the fluid flywheel.

My bus number (if any): RM1699 - Eastbourne Regent V 69

Steve, it could just be the set up of the fuel pumps, we have found that the DPA pumps seem to give a bit more power than the older pumps on the AEC RM engine. The difference between the Regent V and the RM could be fuel pump related, there should not be any difference in acceleration between a clutch and a fluid flywheel although a manual gear change V an auto box might make a difference. Just a matter of interest but isn't the Regent V body a bit lighter than the RM?

My bus number (if any): RTL 960, RML 2667, RM 1585, RMC 1458 and 14 RTs

Brian - what you say is very interesting. I'd always attributed the superior performance of the Regent to the manual box. The vehicles have identical pumps (they're not DPA's) and the Regent weighs in at just under 8 tons, certainly heavier than the RM.

Where I need to change into 3rd to climb a gradient on the RM, the Regent will take it easily in 4th. I'm puzzled!

My bus number (if any): RM1699 - Eastbourne Regent V 69