oil?????

[victor xt]

Hi again mates, like i told you, i did an engine overhaul to my tu3 1.4 avantage and i added 10 w 40 mineral oil for 1000 kms. Now i want to add a good synthetic oil, i bought a mobil 1 5w 50 at low cost but citroen recommends 15w 40 for all zx petrol lines, in the 1995 year, so i guess that's what oil companies and manufactures do when they recommend an especific brand oil but the viscosity i think is an issue ( 15w 40 ) .

My concern is can i use with safety this oil or is aproppiate to modern engines and not the case of the tu3 engine?i know there's a lot of ideas about the oil to use, but in the case of a new engine,like mine , it is better to use the synthetic 5w 50 or is better a semi-synthetic 10w 40 ?

That's all

thanks

[jeremy]

Somehow I think the person who made the engine might recommend a grade of oil that was suitable for that engine. The problem you have is the the manufacturer had a considerable development budget and spent it testing the engine in many conditions, and after that development work it is able to recomment a grade of oil that will enable the engine to function reliably.

Your problem, unless I'm much mistaken, is that your development budget doesn't match the manufacturers, and if you get it wrong - you will pick up the bill. So you've just rebuilt your engine which hopefully is now working well and I imagine your hope is that it will continue to function well for a while - so why not use the oil grade the manufacturer recommends.

[victor xt]

Hi, i'm ok with you, but, like 8 years ago i've had a peugeot 205 with the engine TU3 1.4, same as citroen zx 1.4 TU3 (PSA ENGINE) and peugeot recommends for that engine from 5w 40,10w 40, 15w 40 and 20w 50 grades. The manual is from the manufacturer,not the peugeot chile dealer down here, for example,citroen chile recommends synthetic castrol rs 10w 60 (a racing oil ) like you know for all petrol citroen models except diesel,that included the saxo 1.4 in that time ago,that's because citroen chile and catrol chile agreed with oil usage in their models.

Ok, that's why i don't get it, any comments welcome and thanks again

[fastandfurryous]

Personally, I think it's far more important to make sure the oil is changed on a regular basis that making sure that you get the perfect viscosity for your engine.

There are a number of engines that are all-but identical, but the "recommended" oils can vary wildly in viscosity.
Go for a decent S?/C? rating. (SF/CC or SG/CD seems a good benchmark) and you can't go far wrong. These ratings are independent of the viscosity as far as I know. (although someone else will almost certainly know differently)

Personally, I buy oil by the 205 litre drum, at 15w/40 viscosity, and it goes in everything I own.

[Village]

hello, I'm not sure about what grade of oil you should be using, but I'm fairly sure that if you start using fully synthetic oil, you can't then downgrade to a semi-synthetic or mineral oil at a later date. Having said that, if you've just rebuilt your engine, you'll probably want to give it the best oil you can!

Village

[fastandfurryous]

if you start using fully synthetic oil, you can't then downgrade to a semi-synthetic or mineral oil at a later date.

Why on earth not? if you do a drain and re-fill, then you're not mixing oils (which although not recommended, has never been a problem I'm aware of)

[Kowalski]

It used to be said that an old engine run on mineral oil should not be run on synthetic. This originated in the US, where they don't get the same quality of oils we do and a lot of their engines are based on old engine designs with little evolution. If you have an old engine and run it on and old mineral oil, it wears and you get deposits of gunge making things seal. New detergent oils can clean out the gunge that makes your old worn engine seal. I've never heard it said that you can't go from synthetic back to mineral.

Read the owners handbook or the stickers on the slam panel under the bonnet, once you've discovered what specification of oil the engine needs go and get an oil that matches the spec, change it on schedule (or more frequently if under arduous conditions) and you'll not go far wrong.

I think in the UK, that engine is recommended to run on a 10w40 or 20w-50, perhaps the 20w-50 would be more suitable for a warmer climate. Over here, 20w-50 oils tend to be recommended for older engines, 10w-40 is fairly universal, more modern stuff is going down to 0w-30 oils now.

[victor xt]

Many thanks for posts, today i drained the oil and it was dark with just 600 miles and 3 weeks of age. I don't want to talk about oil brands (wich is the best) but the first oil i used was a Chevron 10w 40 for the first 600 miles,then i drained all that oil and put some new fresh 10 w 40 leichtlauf with MSO2 liqui moly and now the engine sounds very smooth and not that noisier like it was with chevron. The oil have a grey color,never seen that before.

The handbook says 15w 40 and 15w 50 total brand oil company

Well, that's so far, i just want to tell you about the facts with that oil,maybe in the future i'll use the same oil that i'm using now or a good 10w 40 semi-synthetic and the mobil 1 for my sister's mazda 626.

I forgot to say that the synthetic yacco oil 5w 40 vx 600 costs US$30 , that's the reason i wanted to use synthetic for my zx

cheers

[jeremy]

I normally use Morris's turbo-diesel oil in my mega-mileage BX TD but a couple of years ago filled it with a semi-synthetic which seemed noisier - so next time I went back to Morris.

I think moly additives are dark - I can't say I've seen an oil laced with the stuff for sale or even advertised in UK. The thing that really matters here is particle size as I seem to remember reading that Slick which contains teflon could cause a blockage in the bearings as the particles are too large. the scenario is that the additive particles are too large to get round a tight big end bearing so they simply stop an cut off the flow!

I agree with fastandfurryous - frequent changes are more important and the use of good filters.

[Linegeist]

The alleged problem in transition from mineral to semi-synth and back is one I've heard touted before and I suspect is one of those old wive's tales that stem from the days of vegetable-based racing oils. If you swapped over to a veggie oil, you couldn't change back without some form of flushing because the two oil were non-miscible and would lead to all sorts of fun problems at bearing faces. This isn't the case with modern mineral and synth oils.

Having said that, can I suggest that manufacturers, in recommending oils for use in their engines, have half an eye on servicing costs for the end user? If their engine requires a megabuck lubricant every few thousand klicks, then word'll quickly get around that the car's costly to service. Therefore, there's going to be a degree of compromise at the R&D end of things that can be eradicated if the end user's prepared to shell out the beer tokens.

Certainly I've seen 'cheap' oils that have degraded to the point of uselessness fairly quickly after 'missed' oil changes, while their more expensive counterparts have simply soldiered on pretty much intact, protecting the engine pretty much as they should.

One of the things that always sticks in my mind is an engineering lecture I attended at college (back in the days of gas lamps) when we were thrown the question, "How does an oil at, say, 40psi gallery pressure, protect a big end bearing under shock loadings of hundreds of pounds?" The answer wasn't in pump pressure but in flow because, provided there was plenty of (healthy) oil at the bearing, centrifugal force at the crank ensured the oil arrived with enough force to maintain bearing seperation. If the oil was too thick, then it didn't arrive in sufficient quantity to indulge in its little 'fling'

Strewth! .................... did I just woffle all THAT??