Oil viscosity change relative to mileage of engine?

[JD]

My engine has around 60-70,000 miles on it since it was rebuilt, and I'm thinking while the weather is still balmy, I might want to go for something a bit thicker than the Opie Oils cover-all, standard recommendation of "5w-40" that I've adhered to previously :/

[Peter Gidden]

Why?

[JD]

The usual; because I read something online and I now have questions because I am a simple man and also because I have come across criticism/questioning of OO for generally disregarding manufacturers' UK recommendations.

I am aware of the fact that they are an affiliate on here so I don't know how far that goes towards the need for "treading carefully" as far as questions are concerned but a more in depth explanation as to why some here might suggest that,

You have to remember that these cars are getting old now and need a bit of TLC....10w50 offers a bit more protectionn to the aging internals...but each to thier own, run what you want.

[fingers99]

Thicker doesn't always mean better. Check Toyota's recommendations.

[JD]

That doesn't really explain anything. I've been putting 5w40 in my car, despite the sticker on the engine lid recommending 10w30 for a Japanese climate - which is very changeable so I'm guessing 10w30 was the best cover-all solution. I know that supposedly, synthetic oil is better these days than it was when that OE recommendation was made. All I have got so far in this thread is basically, "why are you asking questions? just do as you are told."

If that's the best course of action, fine, but noone has actually tackled the subject of my initial question which was essentially: does it make sense to increase the viscosity of oil for older engines? Considering that common sense tells me that most wear occurs from cold starts, before oil has circulated properly, I understand it makes sense to pick a thinner cold viscosity oil that will circulate quicker - 5w40 is thinner cold than 10w40, right? But these two oils will be the same viscosity when up to temp. I understand that engine internals will be "looser" on older engines and I was wondering whether or not the cognoscenti here at IMOC (Peter et al) might have anything to say about the claim that this might necessitate or benefit from a higher-viscosity oil.

[JD]

more hearsay from here: http://www.mr2oc.com/showthread.php?t=31093

i use 20w-50 synteticblend cause the blend will help with old engine parts.

[dazzz]

Don't know where this is from but may be of some help

Page 7

http://www.puredream.net/mr2/manual/sch ... 0turbo.pdf

[madbasshunter]

Might help explain http://www.imoc.co.uk/forums/viewtopic.php?t=174509

[JD]

Very interesting, if official Toyota service then oil remains the same and the internet is once again, a big pile of BS. It seems to line up with the BGB as well. I'm still interested to know why people would think thicker oil is better once an engine has reached higher mileage

[synXero]

Because people are determined to fidget with absolutely anything in the name of potential usually intangible improvement.

I say this from a position of hobbyist mechanical knowledge - forget internet hearsay and observe the recommendation of the manufacturer. It may well be that the originally recommended oil is no longer the optimal oil for our climate/your form of driving/your mileage/your car's unique tolerances/chaos theory - but I think in 95% of cases, the manufacturer will have put in sufficient testing to cover the probable situations. Stick to what has always worked - these are just machines.

[bobhatton]

I understand that engine internals will be "looser" on older engines

And what parts will they be?

[JD]

I understand that engine internals will be "looser" on older engines

And what parts will they be?

oh i don't know, bob, crankshaft bearings? journals? con rod bearings? the moving parts that are subject to a certain amount of wear after god knows how many heat cycles and miles?

[JD]

Because people are determined to fidget with absolutely anything in the name of potential usually intangible improvement.

I say this from a position of hobbyist mechanical knowledge - forget internet hearsay and observe the recommendation of the manufacturer. It may well be that the originally recommended oil is no longer the optimal oil for our climate/your form of driving/your mileage/your car's unique tolerances/chaos theory - but I think in 95% of cases, the manufacturer will have put in sufficient testing to cover the probable situations. Stick to what has always worked - these are just machines.

bol at chaos theory, but yes, this is what i suspected.

[MR2 Rich]

Got to agree that there will be some wear after 60000 miles but if Bob and Peter say don't do it. You mustn't do it....

Or change to 10w50 and see, it won't do any harm.

[JD]

yup, bob's slightly supercilious/redundant question aside, I am well convinced that it is (in this modern age, at least), nothing much to worry about :/

[bobhatton]

I understand that engine internals will be "looser" on older engines

And what parts will they be?

oh i don't know, bob, crankshaft bearings? journals? con rod bearings? the moving parts that are subject to a certain amount of wear after god knows how many heat cycles and miles?

The only parts that should wear are the piston rings.
The only way to wear bearings is when they have not had an oil flow.
There is no reason to go to a thicker oil, it will take more power to pump it round and will flow at a slower rate than a thin oil.

[MR2 Rich]

What oil and viscosity do you use in your builds Bob? Personally I've always been a fan of the Gulf Competition and have gone with 10w40 in my new build.

[bobhatton]

What oil and viscosity do you use in your builds Bob? Personally I've always been a fan of the Gulf Competition and have gone with 10w40 in my new build.

Gulf is what we have used, not sure if it is 10w40, I will check when I get a moment.

[gnzyza]

I would say regular changes are more important than slight change in grade. I disagree manufacturers do extensive testing, not on all things. for example Honda were/are affiliated with castrol does not mean it's the best oil. Land rover still recommend mineral oil in their tdv engines!!

I would say though the grade of oil is more important with engines that have cam/oil chains.

I use 5-40 full syn, regular oil/filter changes.

[kev8611]

Just to put my 2p worth in.

My daily (BMW 325ti) is now on 124k.

BMW states it needs either 0w30 or 5w30 fully synthetic which is what they were selling me. Normally castrol edge.

I was getting fed up with constantly topping it up so decided to go a little thicker oil on both ways so have been using the Mobil 1 10w60 fully synthetic motorsport stuff.

I am not one for saying you notice differences with changing oil, especially when Im doing it every 5 or 6k. I dont top it up as much as before. Performance, mpg and general engine noise is better than before.