Lubricant/Fluid Manufacturers.

Isn't it often the case these days that for 'std vehicles', even the cheapest (which may not be the nastiest) is good enough and often above the minimum required spec?

I have seen the markups on some of this stuff (I am friends with various shops and garages) and it can differ wildly, not only down to the brand but what 'specials' might be on offer (from the wholesaler or distributor) often down to taking a certain quantity, taking prime position in their sales displays or selling just one range of products.

It's like many 'own brand' products you see in the supermarkets or the tool suppliers ... most come from the same factory and may just be value added via the use of a known badge. ;-)

Re oils .. I will generally use either what I can get at the best price (for all our std vehicles) or will look for what is 'best recommended' if it's something more specialised. Often the small print will suggest it was actually produced by one of the big brands (and possibly be the same stuff) in a cheaper looking tin / name.

A mate recently ordered what he thought was one tin of a generic looking grease and found later he'd ordered a case by mistake. He kindly gave me a can and I noted the small print said it was produced for or by one of the 'Big names'.

My old BMW motorbikes use 6 different grades of fluids (front forks, engine, gearbox, prop shaft, bevel drive and brake hydraulics) and because I want it to last and don't put millions of miles on it, I may splash out for whatever the high mileage enthusiasts (not the couriers ) suggest is 'best' (which isn't always the most expensive).

I think Comma oils are the cheapest in our local car spares suppliers and Morris for most of the motorbike engines (mostly because I can often get it at trade). ;-)

Similar when one of the local car parts or main dealers are doing a special on engine oils (like if you buy 5 cases etc).

You can afford to change a cheaper oil more often, if it's something that dirties the oil up very quickly (like my old Rover 218SD).

Cheers, T i m

You should not be surprised by that.

I am pretty sure that for hydraulic fluids, the different manufacturers will have the same policy as the lube oil suppliers.

They are *very* careful particularly for automotive oils that "their" additive package won't be incompatible with those from any other supplier of grades which could get mixed with it during topping up. The additives pretty much all come from one or two specialist companies. Whilst there's quite a bit of secrecy about exact formulations, the main companies all have excellent analytical chemistry facilities so they have a pretty good idea of what competitors are using. I wouldn't be surprised if there is some sort of gentleman's agreement not to use products which could lead to compatibility problems (maybe brokered by a trade body).

There is one type of synthetic oil (poly alkylene glycol, PAG) which doesn't mix with mineral oil or the more common synthetic poly alpha olefin (PAO). But PAG isn't used in automotive applications.

Not in the sump but it is in the aircon where it uses R134a refrigerant

Yes good point. But of course no danger of mixing with mineral oil!

There is if you have a new air con system with CO2 (Merc since 2017) or very old with R12. They can both transport all types of oil. All it needs is some car maker to work out that mineral oil is a lot cheaper than PAG and can be used with CO2 which is also cheap.

The other new even more expensive gas R1234yf requires a higher spec PAG that costs 3-5x. If you have an accident that vents the refrigerant 40% of the oil exits with it. If replaced/topped-up with the wrong grade compressor life will be reduced.

Just to bugger me up it seems Nissan used PAG in late R12 systems when every man and his dog knows that R12 used mineral. Now I need to find out if the desiccant is compatible with R134a.

OK OK. And you *could* put engine oil in with the brake fluid. But not a particularly likely error.

When I had a summer job in a garage in the 1960's I just managed to stop a young lady on the forecourt putting petrol into the oil filler cap of a Renault Dauphine (IIRC the petrol filler might also have been in the engine compartment at the rear).

as a child I put engine oil in the air inlet of a boat diesel engine, customers cars I have seen with screen wash in the power steering.

And was that the owner who did that or some awful garage?

I don't care as long as it's Fully Synth oil. Frequent oil+filter changes are more important than brand name.

Hehe, I discovered that I always did filter change the wrong way by pouring oil into the filter. Apparently, this is the wrong idea because that oil don't get filtered.

If your new oil needs filtering, then you are in trouble anyway.

Yeah, I've always poured oil into the filter the usual and make sure to smear the rubber ring. But some gurus on internet saz that's the wrong way...

prefilling the filter is fine, the idea is to minimise the time the engine turns before the oil is pressurised and flowing, you can also reduce the wear at first start after an oil change by taking out the plugs (you should, ideally, disable injection and sparks, just in case) and spinning it over till the oil pressure comes up.

Yeah, turning the engine over with sparkplugs removed, the highly volatile air/fuel mix is sent out through the sparkplug holes.

The whole point and reason for Fully Synth oil is to extend the oil change interval. It's 2-3x more expensive as it lasts 2-3x longer. Some cars now have 20K mile oil change (all Porsche and many other German cars), requires a higher spec of oil and they also tend to have large sumps (7L ish). Transits are now on 30K mile oil change. Some HGV can go to 60K but require monitoring.

There are a number of tests for oil condition. One is very easy for DIY.

Drop test.

Put a drip of oil off the dip stick on a filter paper. Wait about 30 min. Observe the way it spreads out, outer rings and the central spot. Center spot is deposits (carbon/metal). Middle ring is oil, should be clean golden. Outer ring can be fuel or water. Fuel goes further than water.

Feel it.

there will not be any if you disconnect the injectors first (as I recommended above). or just power the starter remotely (then all the running gubbins will be unpowered)

I had some weirdo ring me and ask exactly why I had serviced a car twice in a year (he had bought it, as a dealer). I pointed out that the car (a late merc) decides when it needs an oil change, and that as most of its journeys were very short, it was quite likely to need more than one a year. It was quite a bizarre phone call. I also told him that the engine check light occasionally coming on was because of the split supercharger breather pipe (a common fault)

If it's new oil, who cares?

Most injection system will have a main relay somewhere. Just unplug that.

It had probably just come back from the clocker, so had forgotten how many miles it actually did in that time. ;-)