oil

[XxKHxX]

its that time again...to change the oil in my 944. i went to a car shop and they told me to stick with non-synthetic castrol GTX..but i noticed on here that a lot of people use a synthetic oil. i went back to the guy and he said that since my engine is 20+ years old, it would be best to use oil that it's been using for most of its life. he also said that synthetic oils will find cracks and holes in your engine faster, thus causing major leakage. what do u guys recommend? and what kinda weight do u recommend during summer/winter

[legion]

1) Synthetic is better in so many ways, it's just ridiculous.

2) What kind of car do you have?

[Ferrara_racing]

If you use synthetic oil and change it less frequently I don't think it's much of an advantage. What he told you about finding pores I have also heard. The fact is you won't ever perceive any difference in driving or wear for that matter if you change the oil when it's due.

[livewirevoodoo]

I think the wisdom is that synthetic is 'thinner' so it will get past your older seals, not cracks or holes in your engine, per se. What Ferrara says makes the most sense - dyno or synth, take your pick, just change it regularly and the engine will thank you.

[pearldrum]

I run mobil 1 and love it. Run a little thicker than 10w-30. I didn't notice any new leaks when I switched.

[XxKHxX]

im running castrol GTX 10w-40...i think thats a bit on the thick side...and its summer.. i was wondering if i should change teh weight during summer/winter. run lower viscosity during summer and higher in the winter

[mike944]

I use synthetic in all my cars, Mobil 1 in my 944, and 968. No noticable leakage out of the 944, but then again, it has new seals. My 968, well that's another story from a leakage standpoint. I think that's my own damn fault though, i didn't get the oil pan gasket on really well, and that's where it's leaking. Hard to say whether it would leak with dino-juice or not.

I just read a really good, technical article this month on motor oil, it was either in Panorama, or 9 Magazine. Hey, what can i say, i'm an Engineer, i love technical articles on anything! To summarize the article: The wider the "points spread" in oils, the more Viscosity Improvers that have to be added. Viscosity Improvers, without going into detail, are additives, that do NOT have any lubricating properties on their own. The more Viscosity Improvers you need to use, the less oil you're getting. At lower numbers (5, 10) more Improvers are needed for a given "points spread" then at thicker base numbers. A 20-50, while still having the same 30 point spread, has less Viscosity Improvers than 10-40.

The advantage of synthetic, is the base oil stock is more stable, over a wider temperature range, therefore for a given "points spread" significantly less Viscosity Improvers need to be added, and you get more oil. In addition, the synthetic oil base itself has better properties.

I think many people would agree, I would stay away from 10-40, there's too many additives. Depending on your climate, i would use 10-30 in the winter, and 20-50 (or 15-50 synthetic) in the summer.

Don't forget that the 944 series is designed to use much thicker oil, than most modern cars. Use a grade that either matches, or covers the reccomended grade numbers in the owner's manual for the temperature range you use the car in.

[hughett]

I just changed to Redline synthetic oil and my oil leaks intensified.

Harvey

[Ferrara_racing]

This is one of those issues as volatile as abortion. Most mechanics I know feel frequent changes are more beneficial than longer periods with synthetic oil. Their theory being that lubricants are colloidal suspensions designed to hold damaging particles and thus reduce wear. It seems unlikely that a synthetic used in the exact same amount could suspend particles longer and better than regular oil changed in more frequent intervals.

[mike944]

I have to agree. I use Mobil 1, but still change it at 3000 mile intervals.