Advice on oil grades please

Although not for a Land Rover could someone with technical knowledge help me please?

My other car is a Renault Laguna turbo diesel 2.2 2003. The man in the service dept at my local Renault dealership said that the oil to use is 5W30 fully synthetic. I duly filled with this on my last service but have since noticed in the service manual it says to use

5W40. Does it matter that much, should I change to 5W40 immediately or wait till the next service?

Also, does synthetic/semi count for much?

Thanks, Tony

P.S. I wish my td300 could produce the torque the smaller Renault engine produces!

Reply to
Tony
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IIRC problems with failure of turbos on the 1.9Dci being filled with Semi instead of fully synthetic may mean that Renault garages now recommend Synthetic for all engines. The Laguna II 1.9Dci requires fully synthetic oil. I dont know if the 2.2 actually needs it, but best advice is to use it. The 5W30 vs 5W40 difference is negligible, I suspect the slightly thinner grade is now the standard for the range, where 5W40 was normal when the car was made.

Alex

Reply to
Alex

I ran Lagunas as company cars for a few years and recently bought a

2001 1.9 Dci Dynamique cheaply .. Synth all the way!

Sisters car from new, always ran on synth and it's never missed a beat .. apart from the bloody French electrics! I've re-soldered joints for her, repaired the card reader, the rf receiver box and loads of other little niggles.

Would be a fantastic car though if it didn't have the niggles, and if we could get the drivers seat comfortable. ;)

Heh, de-egr, de-cat, straight through centre instead of the silencer and it makes a huge difference. De-egr smooths it out a lot, cleaning intercooler/air intake/plenum also helps. De-cat and de-silencer gives it a flatter torque curve and a bit more oomph ... ;) If you then drive 'normally' the mpg's improve, if you use the power (I do) the mpg stays about the same or worse ... ;)

Best thing I've done though is take it to a diesel specialist for a thorough going over .. £75 a day without it and it's a different car, improvements all round, essentially a good service and a good tune-up to the timing, pump timing etc

Reply to
Paul - xxx

Thanks for that, that's what I'd thought, but nice to be reassured. Tony

Reply to
Tony

Thanks for that, I know about the egr, but if you take out the cat what happens to the emissions at the next MOT? Tony

Reply to
Tony

Way lower .. ;)

Reply to
Paul - xxx

So how does decatting work?

Reply to
Tony

Reduces exhaust back pressure - allows freer exhaust flow.

Reply to
Dougal

Thanks for that, so what's the cat for in the first place?

Reply to
Tony

To reduce the 'toxicity' of the exhaust gases by lowering levels of carbon monoxide, nitrogen oxides and unburnt hydrocarbons.

Search for 'catalytic convertor' in Google or wherever.

In the case that we're discussing, the 300Tdi will pass meet UK's emission rules without the use of the catalyst. Quite why it was part of the UK spec. escapes me.

Reply to
Dougal

To reduce the 'toxicity' of the exhaust gases by lowering levels of carbon monoxide, nitrogen oxides and unburnt hydrocarbons.

Search for 'catalytic convertor' in Google or wherever.

In the case that we're discussing, the 300Tdi will meet UK's emission rules without the use of the catalyst. Quite why it was part of the UK spec. escapes me.

Reply to
Dougal

It does with turbos, synthetic doesn't coke, and its viscosity is much more stable at high temperatures. It is also much less likely to oxidise with the high temperature of the turbo and form sludge.

Semi-synthetic is better for high temperature viscosity, but it certainly does sludge and coke at high temperatures.

Reply to
Paul Saccani

Politics! And proposed more stringent rules.

Dave B.

Reply to
Mr Dave Baxter

Hi Paul, thanks for that, I assume that you would therefore say it's better to go fully synthetic if the engine has a turbo?

Incidentally, I've seen oils specifically labeled for petrol or diesel engines, is this just marketing or is it valid?

Tony

Reply to
Tony

That makes sense because thinking about the MOT, the exaust is only checked for particulates & not co2 or anything else. What difference does decatting make to performance?

Reply to
Tony

That would be my opinion, but bear in mind that my ambient temperatures are usually a good deal higher than those in the UK. I would also suppose that there must be differences in turbo installations that could change those sums. Nonetheless, I have seen plenty of turboed engines with serious sludging issues that were regularly serviced, but with semi-synthetic. To the point where oil starvation has happened, due to the strainer being blocked by the sludge.

I couldn't say, but you do use different oils for the two services. I use the API service classifications, rather than the marketing blurbs. These are empirical performance standards. You will usually see a dual classification on oils, such as API SJ/CF. The Sx is the petrol service category, whilst the Cx is the Diesel service category, with the second letter following the alphabetical sequence, where each increase in the letter covers all previous service categories and adds new requirements. So in the above example, you might use it in a Diesel engine, but you may need to change the oil sooner.

Diesel requirements are way more demanding than petrol in many areas. Actually, they can be helpful in desludging abused petrol engines.

Reply to
Paul Saccani

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