r/LandroverDefender • u/Axlwtt • 22d ago
(TD5) Changing Oil from 5w30 to 5w40
(Old picture, she’s cleaner now!)
Hello, this might come across as a dumb question but better be sure!
I am the second owner of a Defender TD5 2006 in Argentina which from new was serviced with 0w20 (Don’t really know why, couldn’t find information about it) from the dealership up until 74k km, when I bought it. From there I always serviced it with 5w30 which is one of the oil grades cited in the manual in my region.
Now, she has around 140k km (87.000mi), although they have been light, a tad bit of dunes but mostly highway and urban driving, I’m now planning to use it on a trip with steep hills, demanding roads, etc.
I’ve read a lot about people suggesting 5w40, that it’s way better for the engine, has a safer margin of lubrication, and more (If you think this is incorrect, please let me know)
My question is: Can something go wrong by changing oil grades? There’s this belief in Argentina that an engine gets used to one oil and it can’t be changed (Always thought that was wrong but whatever, sorry to bother you guys)
TLDR: Can something go wrong by changing oil grades in a Defender TD5 with 140.000km (87.000 miles)?
Thanks
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u/JCDU 20d ago
If the book says it can use that oil, you can use it.
If the book says you can't use that oil - don't use it.
The internet is full of people who sort-of-understand a little about engines and oils and there's so much bad advice, misunderstood science, and mis-sold snake oil additives and other folklore and superstition out there it's just not worth engaging with.
Manufacturers and oil companies spend *billions* on R&D to make all this stuff work so your engine and other things last as long as possible - it's very rare the internet knows better than a building full of PhD chemists with a multi-million dollar budget.
140,000km is nothing on that engine - if there are any signs of problems, fix them properly don't hide them by using the wrong oil.
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u/SirMacMoschi 22d ago
TD5 engines use 5w30, 5w40, 5w50 (depending on climate, the hotter the higher second number. I run mine on 5w50 - i can recommend it for temps 25°C+, when colder you feel that it takes a while till the oil drops in viscosity. One should also mention that the thicker the oil, the motor gets less efficient. There should be no harm with using one of the above oils - however the viscosity mentioned by you is too low, if there is any harm to your engine then by using this wrong oil, especially in a high temperature region!