Switching To Synthetic

[Carl83911]

I've decided to take a chance by switching to Mobil 1 supersyn 15w-50. Anyone using this grade? How is it working for you? I'll be crossing my fingers and hope that no leaks occur. We're taking off Saturday for a weekend jaune up north on Hwy 1 to Fort Bragg, CA.

It's going to be in the 100's in the sacramento valley over the weekend so the coast will be in the 70's.

I was in the MobilOil site and it recommended full syn Mobil 1 trk & suv 5w-40 for my car.

[Rod.911S]

Carl,
I've got M1 15W50 in my '77. It had a rebuild 35,000 mi ago and has the upgraded chain housing covers (that go with the hydraulic chain tensioners) and Carrera valve covers.

It doesn't leak. I've only had the car 3 months but have the records that indicate its had mostly synthetic oil but with the occaisonal non-synth change as well.

I'd go go for it.

[efhughes3]

Am I the only one using blends? I use Valvoline Dura-Blend 20/50, and I think it is great! Even after DE's and Texas heat, the oil from my 122K motor looks great when I change it. I don't run the risk of the seal problem, and I get the benefit of synthetic IMO.

[serge944]

If you're concerned about leaks, why would you want anything but the most viscous M1 oil.

I switched to Mobil 1 in my old car and the leaks went from adding a quart every 1000 miles to 300 miles.

Consider a synthetic blend (the castol one isnt bad). I know widebody911 uses it and it works quite well, even on the track, with just minor leaks.

[Carl83911]

Originally posted by Rod.911S
Carl,
I've got M1 15W50 in my '77. It had a rebuild 35,000 mi ago and has the upgraded chain housing covers (that go with the hydraulic chain tensioners) and Carrera valve covers.

It doesn't leak. I've only had the car 3 months but have the records that indicate its had mostly synthetic oil but with the occaisonal non-synth change as well.

I'd go go for it.

____

Just had major tune up approx 2-3 weeks ago. New valve cover gaskets, already had the upgraded chain tensioners and I believe I have the Carrera valve covers. My compression test was excellent at 165, 164, 165, 164, 165, 164. The last grade I used was Castrol GTX High mileage 20/50.

Just curious though, I know that not all the oil drains out and that about 2 qts remain in the system. Is it harmful for the Mobil1 supersyn to mix with old oil? I really don't feel like disconnecting any of the oil lines to drain the rest. I was thinking of using my old shop vac to suck out the rest through the oil tank.

[patkeefe]

Carl:
There is lots of information (and mis-information) regarding oils.
Here's some light reading for you. There are some very knowledeable oil guys here though. The beauty of this board is that there are lots of guys with diffrent areas of expetise, in which they know stuff cold.
Oil is pretty important, so read up.

I am likely one of the minority who has dino, and refuses to switch...had a leak problem once before. I only have to drop a bowling ball on my foot once to know it hurts.

Pat

when mobil one 15-50 is gone, what will you use?

Why are new engines OK on synthetic but old ones leak?

[Paulporsche]

Not an oil expert, but to answer your question, I've been using Mobil1 15W50 for the past year and a half without any leaking.

BTW rebuilt, enlarged engine has approx 75000mi on it.

[Carl83911]

Originally posted by Paulporsche
Not an oil expert, but to answer your question, I've been using Mobil1 15W50 for the past year and a half without any leaking.

BTW rebuilt, enlarged engine has approx 75000mi on it.

____

On both you 911s, how old are your seals and gaskets. Mileage on your 911s?

[msterling]

Using M1 15w50 in my '88 3.2 Carerra. Doesn't leak a drop. I think it has had synthetic only since day one. Oil return lines have been redone once. Only 40k on the clock so far. The PO only put on 16k in 12 years! It seems to use about 1qt/1500 miles.

I don't know if I would switch TO synthetic after many miles of dino in a car but I'm comfortable with staying with it when there are no apparent problems.

[donstevens]

Originally posted by Carl83911
____

Is it harmful for the Mobil1 supersyn to mix with old oil? .

No problem at all. Today's synthetics are fully compatible with dino oils. You will have an 80/20 blend of synth/dino for the first change interval (assuming that you have a 10 qt capacity and you leave 2 qts in the lines) and once you change the next time, there will be almost no dino left.

Go with the 15/50 viscosity.

Amsoil makes a 20/50 high performance synthetic oil for those who want to keep the same viscosity grade and try something different.

Don
www.lubedelaer.com/dstevens

[Svensson911T]

10/40 synthetics and it is working good

[livi]

Last year Mobil 1 0w40. Untouched engine at 90k miles. No leaks.

This year Castrol 5w40. No leaks.

[OffCamber00]

I just switched from Kendall GT1 to Mobil 1 15-50 Extended Life. 88 Carrera, stock motor, 114,000 miles.

The slight weeping I have at my cam towers has not worsened. Oil consumption has not changed.

[azasadny]

Originally posted by donstevens
No problem at all. Today's synthetics are fully compatible with dino oils. You will have an 80/20 blend of synth/dino for the first change interval (assuming that you have a 10 qt capacity and you leave 2 qts in the lines) and once you change the next time, there will be almost no dino left.

Go with the 15/50 viscosity.

Amsoil makes a 20/50 high performance synthetic oil for those who want to keep the same viscosity grade and try something different.

Don
www.lubedealer.com/dstevens

I just changed my oil and used the AMSOIL 20W50 Racing Oil for the first time. I always use the Mahle OC54 filter and I replaced that too. I just put 3700 miles on the car, so I wanted to get the oil changed and try the 100% synthetic AMSOIL since everyone I know uses it and raves about it. We'll see...

[movin]

So many "synthetics" today contain a mix of type III (HC dino) and IV base stocks that you're really getting a blend. Some suggest even Mobil 1 is. The leak question is a non-issue and shouldn't be a basis for choosing an oil unless your engine is using NOS seals that were manufactured over 25 years ago.

[chuckr]

I just did an oil change this past weekend on my 88 911.
I've been doing way too much reading here and on other sites.
I like synthetics and used to use Redline 20/50. It got hard to
get here where I live. All my reading lead me to Mobil One
V-Twin oil. V-Twin is VERY expensive !!! about $8.00 a quart
at Wal-Mart. Wal-Mart also sells Mobil One 15/50 full synthetic
by the 5 gallon jug for about $24.00. I'm a risk taking kinda guy,
I also am not wealthy so $100.00 oil changes are out of the
question. I was spending about $70.00 for the Redline so...
I thought try 5 quarts of V-Twin and 5quarts of the 15/50
kinda make my own blend thing. I feel good about the combo
from what I read, this should do the trick. The way I see it...
oil is kinda like vitamins. You get what you think you need
to protect you !

Chuck

[Craig 930 RS]

An old engine such as a non-rebuilt 1983SC that has seen dino oil all it's life may well result in some significant leakage with a pure synthetic.

Be ready for it.

[Tim Hancock]

Originally posted by movin
So many "synthetics" today contain a mix of type III (HC dino) and IV base stocks that you're really getting a blend. Some suggest even Mobil 1 is. The leak question is a non-issue and shouldn't be a basis for choosing an oil unless your engine is using NOS seals that were manufactured over 25 years ago.

Hmmm, tell that to my 2000 Audi A6 2.7T (110,000 miles) that just started leaking within a few days of switching to synthetic along with a good friend who just switched his '99 BMW 325 (125,000 miles) to synthetic and now also has a leak. I am not calling you a liar, I just have personal experience that leads me to believe that the high mileage synthetic switch can indeed sometimes cause leaks.

[Craig 930 RS]

Agreed, Tim. The hell it isn't an issue.

It is a "known" and happens more often than not.

[FastCarFan]

I switched to Mobil 1 last summer at 50,000 miles. I was concerned about leaks (it had never leaked a drop before). So far, it still has not leaked at all.