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Discussion Starter #1
In my handbook for my 2.5 its recomends 5W-30 oil for ambient temperatures regularly below 0degC and 10W-30 for anything above. Are we all following these guidlines?
 

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i tend to use either a 5w 30 or a 5w 40 but always fully sythetic
 

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I use M1 5w30, as recommended. If I can find it for the winter, I change to 0w30.

I don't believe the owner's manual recommends 40-weight oil, but it won't hurt anything, necessarily, since it's so close to 30-weight... 50 is a bit much, though I hear of some people running it... not sure why.
 

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i use 5w-30 all year round, never had any problems.. but up here there is more cold days then hot ones so i just stick with it... no point one day its 28 next day its 8 degrees out
 

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I'm running 5W30 all the time...full synthetic.
 

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I lives in the desert, and it only gets below freezing (32) at night, when I'm usually not driving, so it's 10w30 full synth year round.
 

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Did you all make the switch to synthetic after major engine rebuilds, or at least new seals & gaskets all around?

I want to go synthetic, but have always heard that making the switch in a high miles engine will ruin the seals & gaskets = leaking like a siv.

Already my car is like :drinkup:with oil...
 

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mosheen said:
Did you all make the switch to synthetic after major engine rebuilds, or at least new seals & gaskets all around?

I want to go synthetic, but have always heard that making the switch in a high miles engine will ruin the seals & gaskets = leaking like a siv.

Already my car is like :drinkup:with oil...
I feel the only reason you shouldnt switch to synthetic is if your engine burns or leaks oil then you will be spending more due to the price of synth. A 5w30 dino has the same viscosity as a 5w30 synth, so theoretically no more should leak out.
If your engine is still tight, change over to synth ASAP because the benefits outweigh the cost in the long run.;)
 

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what about useing a sythetic blend
 

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I use 10w30 all year long, 'cause I have a slow oil leak and I figured a little thicker oil won't leak as fast. We do have some pretty cold days here in the winter, but the car stays in the garage overnight, and if it's below 15 during the day I always head out at lunchtime so my poor engine isn't stone cold when I leave at the end of the day. I haven't had any problems so far.
 

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As far as switching to synthetic in a high mileage engine, I wouldn't recommend it. Dino oil is best for high mileage applications mainly because of it's ability to swell and condition the seals as well as "patch" leaks. By switching to synthetic oil you are introducing new detergents that will break down those improtant buildups of sludge and may actually cause MORE leaks. I've heard mixed reviews but there have been too many negative experiences than I'd care to ignore, just use something like 5w30 Castrol High Mileage, it's good stuff.
 

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Discussion Starter #14
I've been advised that 5/40 is a suitable step up from 5/30 to allow for wear of the engine, subject to maintaining the correct quality of the oil beacuse it is also relevant to how many miles or how worn the engine is. The figures quoted by the vehicle assemblers are for ideal engines (new or nearly new). As we all know there are more out there in a poorer condition than there are out there in such top condition. What do you reckon?
 

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I could see how using an oil with a higher running temp viscosity could help with leaks (on a minor scale), other than that I don't see any huge benefit in the long run. I've actually used both and didn't see any difference, I'd just stay with the manufacturer's recommendation as any weight of oil in the general area will probably yield negligible differences.
 

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ChicagoGirl: 10w seems a little high for a Chicago-area car. 5w would be better for you, particularly in the winter. Remember, the first number is the cold-flow ability of the oil... winter cold will thicken an oil, so a lower number is well advised. Once it's warm, it's a 30-weight oil, so 5w30 and 10w30 would be similar when warm, and hence shouldn't affect leak rates.

Danjamin - You are correct, cleaning out an older engine can increase leakrates. This is why an engine flush is recommended, and if you notice, they always recommend a regular oil during this process to help the seals swell back up. Obviously, synthetics can clean the engine too, but they don't swell seals as readily as dino-oils do. As for the seal-swelling in the first place, I can attest to this behavior, as I performed an AutoRX and have personally noted a reduction in oil consumption. Many other AutoRX users have noted similar results, too.

kman - not sure why a thicker oil would make more sense in an older engine. Sure, it probably reduces leaks, but it also reduces flow rates, which means you're making the engine work harder due to the lower oil flow. Oil pressure is meaningless if there is no flow, and vice-versa. So, thicker just doesn't make sense to me, but hey, what do I know.

If you're having leak issues, you may want to fix the problem, rather than band-aiding leaks. I strongly support AutoRX, but there are other similar solutions available, too.
 
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