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Discussion Starter #1
Probably a bit of a leading question, my GTV has done 125k miles, the last 40k on castrol high mileage oil, it was dynoed last week at 153 bhp (3 more than it should make) so i think I may stay with castrol, but all advice is welcome.
 
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Probably a bit of a leading question, my GTV has done 125k miles, the last 40k on castrol high mileage oil, it was dynoed last week at 153 bhp (3 more than it should make) so i think I may stay with castrol, but all advice is welcome.
Valvoline MaxLife!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :lol:

I think the reason it made 3 more was probably due to the freezing weather :)
 

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My vote goes to Mobil 10W 50. On the TS I keep it slightly over the max line and the variator will never make any more noises between T-belt services (I'm thinking of skipping changing the variator on the next belt change to see if it will last). The V6 is going to get Mobil 10W 40 from now on as well.
 

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Discussion Starter #4
yeah, cold air = denser air = more oxygen = bigger bang, but hey the point is it's done a lot of miles so take the 3bhp off for cold air and its still making factory bhp which means someone has done something right along its history, the old addage "if it aint broke dont fix it" suggests i stay with castrol, on the other hand maybe it did its first 85k on valvoline max life!, doh:)
 
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In this weather, it could well be up by 10bhp compared to warm summers day... shame its too cold to put it to good use.
 

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Back to the subject of oil, there is many threads bout oil so a seach would not do harm

but I would use a decent mobile 1 10-40w semi syn oil, or a 0-40w fully syn.

But any decent make of oil will be fine, I don't really rate castrol oil but this is my opinion
 

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Discussion Starter #7
Yes, i think ur right ICB (hope you dont mind the abbreviation), pretty much all premium oils are up to the job, spoke to the last owner after my previous post and he said that he had used various oils over the last 40k miles but always good quality and changed oil every 3k, i only do about 8k a year so that service interval wont be too costly.
 

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Yep you got it, not sure how true but I was told that better oils such as fully sys don't make no difference over 60k as the damage would have already been done
 

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Discussion Starter #9
As i understand it synthetics keep their properties better at higher temperatures, in fact before someone shoots me down on that i will wiki it and come back with a more robust answer:)
 

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Discussion Starter #10
I was right...ish.

Advantages
The technical advantages of synthetic motor oils include:[citation needed]

Measurably better low and high temperature viscosity performance
Better chemical & shear stability
Decreased evaporative loss
Resistance to oxidation, thermal breakdown and oil sludge problems
Extended drain intervals with the environmental benefit of less oil waste.
Improved fuel economy in certain engine configurations.
Better lubrication on cold starts
Longer lasting engine life
[edit] Disadvantages
The disadvantages of synthetic motor oils include

The lower friction may make them unsuitable for break-in (i.e. the initial run-in period of the vehicle) where friction is desirable to cause wear. Improved engine part machining has made break-in less critical than it once was, though. Many modern cars now come with synthetic oil as a factory fill.
Potential decomposition problems in certain chemical environments (industrial use dominantly)
Potential stress cracking of plastic components like POM (polyoxymethylene) in the presence of PAOs (polyalphaolefins).
Synthetics do not hold lead in suspension as well as mineral oil, thus caution is advised when the engine is run on leaded fuel.[citation needed] As an example, leaded fuel is still commonly used in aviation (avgas).[12]
In July 1996, Consumer Reports published the results of a two year motor oil test involving a fleet of 75 New York taxi cabs and found no noticeable advantage of synthetic oil over regular oil.[13] In their article, they noted that "Big-city cabs don't see many cold start-ups or long periods of high speed driving in extreme heat. But our test results relate to the most common type of severe service — stop-and-go city driving." According to their study, synthetic oil is "worth considering for extreme driving conditions: high ambient temperatures and high engine load, or very cold temperatures." [14]
Synthetic oils are not recommended in automotive rotary engines.[15]
 

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I'd guess concern that, if the current service history is infrequent with poor quality oils, there may be deposits that synthetic oil will flush out and block smaller oil galleries :( IMHO if you've got to 125K miles without a problem on semi-synthetic, you might as well continue on semi-synthetic :)
 

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Stay with Castrol because their oils have less detergents and if you use another brand with many detergents the sludge can get into your oil pump and bye-bye bella.

Another thing: once you go from semy to full synthetic its advisable not to go back to semy again.
 

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Stay with Castrol because their oils have less detergents and if you use another brand with many detergents the sludge can get into your oil pump and bye-bye bella.

Another thing: once you go from semy to full synthetic its advisable not to go back to semy again.
Castrol is just like any other oil, the detergent levels will be similar on a like for like oil.

If the engine is in good shape swtiching from one sort to another, and back again will be fine.

To the OP, if you look up your model here Car Engine Oils You should find a selection of suitable oils.

Cheers

Guy
 

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Discussion Starter #17
Thanks, the castrol high mileage oil that the previous owner used evidently has additives to prolong the life of the seals, maybe that works who knows but as it obviously didn't harm the engine and its relatively cheap i think i will carry on using it, thanks for the link it suggested magnatec which i have always used on my 944, toss up between the two then:)
 

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Castrol high mileage is 15w-40 isn't it?

If it is it's the wrong grade and you shouldn't use it.
 

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Castrol high mileage is 15w-40 isn't it?

If it is it's the wrong grade and you shouldn't use it.
yep, wrong grade... it is also a basic mineral oil...
 

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Discussion Starter #20
Must admit read the blurb about the seals n saw the price but didn't look at the viscosity, wouldv'e done before buying though, obviously, magnatec is 10/40 though, actually after years of using 10/40 i have just realised im not entirely sure what those fogs mean, time for wiki again!
 
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