Can anyone give me the right answer. How often should I change my engine oil. I've got a manual '93 stock J-spec with 52K miles on the clock?

I don't drive like a lunatic, but I love the acceleration!!!!

Nissan say every 4,000 to 6,000 miles.

I do it every 4,000 which is about what every one on here does. Some people do every 1,000.

Stuart

2-3k miles for me.

3k for me but will probably be good if I left until 5-6k

 

------------------

Every 4k for me without fail.

 

Matty.

 

------------------

3k for me, but I use my car everyday and do many short ~15mile journeys. If I did longer journeys I would leave the oil in longer.

Thanks guys! It looks like the 3K change is the safest, especially if there's a lot of town driving.

 

Now my next question - what oil?

Shell Helix Ultra is the best.

 

I work for Shell and have seen the results

Magnatec.......

 

Every 4k.......

 

Matty.

 

------------------

Most top-teir oils do what Magnatec adverise, but Shell oil is the best overall.

 

 

castrol rs 10-60 expensive but worth it!

I use Shell Helix Ultra and very pleased. I use the car everyday for my 80 mile commute and change the oil every 3/4k.

 

------------------

Z first and anything else is secondary!

John Newcomb (NukeEm)

www.geocities.com/jn300zxtt

I heard this story at work...

 

Ford gave us an engine to run our oil in. We ran it for a while, then gave them the engine back to examine. They got back to us and asked why we had drained the engine and put fresh oil back in bfore sending the engine back. To which we replied.."But we didn't! The oil in the engine is the oil that has done *** hours !"

 

Ford's reply was ..."We have never seen an oil in such good condition after an engine test !"

Shell Helix Ultra every time.

 

Magnatec adverts are clever, but the oil's not that special. Cold start protection is provided by friction modifiers - present in most (if not all) top-tier oils.

 

We have done comparative tests with our oil against Castrol, etc. etc. and ours was the best overall. Honest !

And compared to Mobil 1 (0w-40)?

 

-Andrew

We probably tested Mobil 1 and we were better, but couldn't swear by it. Mobil 1 is very good tho', if Shell is better, there's not much in it.

Redline 10/30 EVERY 3000 miles.

 

Do it and your engine will thank you

 

 

 

------------------

->Glen

-

Skyline GT-R

'You dont so much drive this car -

as hang on for dear life..'

J.Clarkson

Any well known brand's synthetic oils will be pretty good IMHO.

 

There are many tests for oils. If oil comes out clean after the engine has been run then that engine was spotlessly clean AND all the surfaces were well mated. Neither conditions are likely in a typical consumer engine. Of course it's possible that an oil is so good that badly mated surfaces have been protected but if the oil was able to get completely fill the gaps between those surfaces then the engine tolerances were crap - and surely oil would have leaked through piston rings etc.

 

In my opinion, I would rather see the results of oil which HAD been soiled (as happens in normal use) on the internal surfaces.

 

I'm not suggesting that in certain tests, Shell oils don't come out best - I have no reason to question that.

 

However an oil will go in clean and come out dirty. In the meantime, it will have affected engine wear. It's the overall effect of the various states of oil cleanliness over many many oil changes that makes an oil the best. And I really doubt that any manufacturer has done enough testing to really prove it.

 

Spend your money and take your pick - just make sure you spend a reasonable amount of it !

 

Dave

You'd be amazed how many test we put our oils through and that includes 'normal' driving conditions in real cars as well as test beds, screener tests, industry tests etc. etc. We measure wear, piston cleanliness, deposits, dispersivity, antioxidancy, fuel economy, seals compatibility, friction, etc. etc..

 

A key aspect to oil ageing is that base is there to neutralise acids which buildup as a result of water and SO2 gases etc. dissolving in the oil. When the base is neutralised by the acid, the viscosity of the oil rises dramatically. This is bad for any engine, affecting performance as well as wear. Shell's top-tier oils have plenty of base (called overbasing) with high additive treat rates. Others have high treat rates, but probably a bit less than Shell's. So they don't last as long.

 

 

Nelson,

 

I'm sure you're right about me being amazed by the tests. So tell us - I'm genuinely interested !

 

But surely other companies put their oils through similar tests ???

 

When I was kart racing I would rebuild my engine after every 1.5 hours or so of running.

 

I used many oils and found that Castrol R was the best although Shell did come second best. My engine would normally manage 10 - 12 hours before rebuild and I'd normally get a couple of hours more from a Castrol run than a Shell. Resbuild were based on observation of the bore and compression testing.

 

Are you directly involved in oil development ? If so, what would your thoughts be on judging 4 stroke oil based on my experiences of 2 stroke ?

 

Dave

I'm relatively new to the group at work, so I'll ask others for more details..

I have no experience/knowledge of 2-stroke. I help develop oils for petrol and diesel passenger cars, with some Heavy Duty (truck) diesel oil work.

 

I think 2 and 4-stroke are completely different beasts - isn't 2-stroke oil used as the fuel and the lubricant ? Very primitive !

 

Different oils from one company have different qualities - when I say Shell is best I mean Shell Helix Ultra, shell's top performer, designed to meet the most stringent industry specifications. Lower-tier Shell products may not be so special, but you wouldn't put them in a 300ZX !

 

Yes, other big companies run similar tests. I was trying to point out that our findings and comparisons are not just based on a few theoretical concepts or half-baked laboratory simulations. Remember, Shell formulates oil for the top F1 team (Ferrari) and Ferrari passenger cars(Helix Ultra Racing).

 

I'll get back to you when I have more info/facts.

Didn't feel too primitive when it was taking me from 20 to 80 mph in 4 seconds (from a 100cc engine screaming away at 18,000 rpm by my right ear) !

 

The oil isn't actually used as fuel - it's mixed with the fuel.

 

I guess it can be argued as primitive but supplying oil with the fuel does help with distribution inside the bore. It's doing the same job but it's delivered from the top rather than the bottom. In my engine, there was no oil running through the crankcase at all - it was all running in sealed bearings. Surely quite advanced ?

 

It made for seriously low friction but was also a fairly major contributor to the 10 hourly rebuilds. And I guess that could be reasonably argued as undesirable in a Z.

 

It'd be good to post more about the testing that oils undergo. Especially in light of the never ending 'how often should you change your oil' debate.

 

With your insight from the industry, what are the major factors in determining appropriate frequency ? Are things like humidity of atmosphere a factor ?

 

Dave

Gentlemen,

 

What have I started??

 

Looking at the response I would think that, as in most things in life, you get what you pay for. SE Nissan, where I take the beast, use a secondary brand (Morris?). Any details on this?

I think the reason 2-strokes mix oil in the fuel is because the fuel mixture sits in the crank-case before going through the transfer ports and into the cylinder.

 

Because of this you can't have normal crank lubrication - hence the sealed bearings.

 

The modern direct-injection 2-strokes can use 4-stroke style bearings and lubrication.

 

 

Anyway - I've never had to do a normal oil change yet - just change it at each rebuild (about 2k to 3k miles ! )

Harry,

 

SE always recommended Castrol RS when I used them. I had no problems with it but, like the vast majority of others on here, I couldn't actually comment on whether that made a blind bit of difference to my engine internals. But they didn't go bang so it can't have been awful !

 

Mac is a consistent user of SE's services - be worth seeing what he uses. I'd be fairly sure that if he had gone away from Castrol that he'd have discussed it.

 

Dave