help my mpg

[KozmoNaut]

Diesels are 12,000miles/12months. It's widely regarded that 6,000miles/6months is ideal for diesel engines. Even haynes reccomend it!

"Widely regarded" and "commonly acknowledged" and so on are not equal to "it has been proven" :-P

Either way, I'll never trust Haynes completely. "Installation is the reverse of removal", indeed! They're good for looking up bits of information and for general procedures, but I prefer to trust the manufacturer for anything critical. The difference in the level of detail between Haynes and a factory service manual is enormous, usually Haynes tries to cover far too many models and variants in a single book and lose out on critical details, some times they lose out on details while still not covering enough models! For instance, the Haynes manual for the D9 406 doesn't even cover the 2.0 HPI, the 2.2 petrol or the 3.0 petrol.

Don't get me wrong, it doesn't hurt to change the oil more often. But considering the fact that there are 2.2 petrol 406s on the road with over 400,000km on the standard Peugeot maintenance and oil change schedule, I'm inclined to place my trust in the people who designed and built my car.

Modern synthetic oil is some seriously impressive stuff and for just about anything on the road these days, a yearly oil+filter change with decent fully-synthetic oil is perfectly fine, unless you do nothing but "severe duty", specifically short trips, very cold weather, very dusty conditions or very high yearly mileage. I'm a bit wary of super-extended oil change intervals as well, but a yearly change is not an extended interval at all, it's a shorter interval than most engines were designed for, with the average mileage that people do.

[Bailes1992]

Diesels are 12,000miles/12months. It's widely regarded that 6,000miles/6months is ideal for diesel engines. Even haynes reccomend it!

"Widely regarded" and "commonly acknowledged" and so on are not equal to "it has been proven" :-P

Either way, I'll never trust Haynes completely. "Installation is the reverse of removal", indeed! They're good for looking up bits of information and for general procedures, but I prefer to trust the manufacturer for anything critical. The difference in the level of detail between Haynes and a factory service manual is enormous, usually Haynes tries to cover far too many models and variants in a single book and lose out on critical details. For instance, the Haynes manual for the D9 406 doesn't even cover the 2L HPI, the 2.2 petrol or the 3.0 petrol.

Don't get me wrong, it doesn't hurt to change the oil more often. But considering the fact that there are 2.2 petrol 406s on the road with over 400,000km on the standard Peugeot maintenance and oil change schedule, I'm inclined to place my trust in the people who designed and built my car.

Modern synthetic oil is some seriously impressive stuff and for just about anything on the road these days, a yearly oil+filter change with decent fully-synthetic oil is perfectly fine, unless you do nothing but "severe duty", specifically short trips, very cold weather, very dusty conditions or very high yearly mileage. I'm a bit wary of super-extended oil change intervals as well, but a yearly change is not an extended interval at all, it's a shorter interval than most engines were designed for, with the average mileage that people do.

But Petrols don't dirty their oil like diesels!
Diesels have stuff like EGR's to contend with which massivley increases the accidity of the oil and also increases the amount of particulate matter in the oil increasing abbrasives by huge amounts!
You can create the most perfect oil in the world but I still wouldn't want huge amounts of soot floating around in it.

[Bailes1992]

Oh and as far as I'm concerned all manafacturers are concerned about is getting the car out of the warrenty period without issue. They don't care what state the engine is in 10 years time!
That is quite obvious with the new service schedules of modern cars! I don't want my car serviced once every 2 years! Thats far too long.

[KozmoNaut]

But Petrols don't dirty their oil like diesels!
Diesels have stuff like EGR's to contend with which massivley increases the accidity of the oil and also increases the amount of particulate matter in the oil increasing abbrasives by huge amounts!
You can create the most perfect oil in the world but I still wouldn't want huge amounts of soot floating around in it.

Petrol engines have EGR as well. Modern synthetic oil does a really great job of suspending all of the abrasives and soot that the filter doesn't catch. It's true that acidity and moisture in the oil are big factors, but they are pretty much eliminated by getting the oil nice and hot. If most of your trips don't warm the oil fully, you should technically be on the "severy duty" schedule. This happens mostly when people mistakenly buy a diesel for the high fuel mileage, and then proceed to only putter around town on short trips. Don't needlessly use your car for short trips, use it within its design envelope and the factory recommendations are actually rather conservative, at least for the 406.

Oh and as far as I'm concerned all manafacturers are concerned about is getting the car out of the warrenty period without issue. They don't care what state the engine is in 10 years time!
That is quite obvious with the new service schedules of modern cars! I don't want my car serviced once every 2 years! Thats far too long.

This is at least partially true, but it's always been true. On the other hand, manufacturing tolerances and oil technology have made vast improvements even compared to just 10 years ago. I have to say, despite the increased mileage allowances between services and oil changes, I've never seen any recommendations for 2 years between services, 1 year is the standard, as it's always been. But the mileage "allowed" within that year certainly has gone up.

[Welly]

Kosmo is right about the oil it is far better than it used to be and a good fully-syn won't shear down like older mineral oils used to. Manufacturers have extended the intervals so that the running costs look competitive to the lease companies etc and lets face it apart from enthusiasts like us who else would argue that the service schedule is 'wrong'?

My petrol Volvo takes 7ltrs of *very* expensive fully-syn and I have it changed every 12 months (8000 miles) and even then it is still a golden colour on the dippy. It would be no real benefit to do it twice a year.

Diesels - I kinda see what bailes means; it would be 'nicer' to treat the engine to 6-monthly's and a diesel's big-end is under a lot of strain when labouring (and most drivers labour diesels) and the oil gets dirty easily etc. I don't really think it needs doing so often but if you want to then cool.

[Bailes1992]

Petrols are a total different kettle of fish.

Petrol EGRs work well.
Diesel EGRs don't work very well at all and completely destroy the oil.

Either way diesel have have filthy oil compared to petrols.
I may send my oil off for analysis at the next interval just to see what's in it. Bare in mind my EGR has been disabled.

I am planning on dropping down to a 0w30 oil for added winter protection.
I am tempted to try millers nano drive oils but at £90 for 6L I would have to adhere to 12k/12moth intervals.

[Welly]

I may send my oil off for analysis at the next interval just to see what's in it

£126.50 later and the results are in...................it's Oil

[dave406]

any idea on petrol doont wanna go smaller then astra/307

[Bailes1992]

any idea on petrol doont wanna go smaller then astra/307

It's okay, you don't need to repeat yourself

Personally I think the MK1 Focus would be a good bet (Assuming you want something around the same age as the 406?). The parts are cheap, they are pretty reliable and easy to work on!
1.6 Petrol is pretty gutless low down, you have to rev it to make it move but they will shift if you get the hammer down! Mine would do 40-50mpg on a fast cruise and about 30-35mpg around town.
1.8/2.0 Petrols are both a much better low down but there is no difference in fuel, you might aswell just go for the 2.0!

Although I hope you aren't changing just because the fuel economy is poor in the 406. You won't get much better no matter what you buy!

Saying that my Mums 1.2 Panda is awesome on fuel around town! Sometimes doing 45mpg!

[steve_earwig]

Does it have to be automatic?

[dave406]

nope just needs to be good mpg around town and good on occasional motorway runs

[GingerMagic]

How about a Hdi 110, good all rounder, great on fuel and quite a few autos if thats your thing..?

[dave406]

Thats what im driving now i and it doesn't have to be an auto i understand a Manuel is more efficient

[steve_earwig]

Fair enough, there was someone a few months back who had to have an automatic due to disability but I can't remember who it was, so I thought I'd better check.

So, if the size of the car is ok look for another one but manual, if it's too big or you think you could get away with something a bit less roomy look for something a bit smaller.

Manuals are more efficient unless you do lots of motorway miles when they start to catch up, although if you're only doing lots of short journeys then perhaps a petrol would be more suitable.

[Bailes1992]

You'd be lucky to better 30mpg around town no matter what you buy!