im considering going to synthetic, what do you guys think, my cars an 86 na, no oil leaks, 67k, would it be good to switch to mobil 1?

 

Of course! There's no reason not to switch to better oil.

 

of course i want better oil, i just have heard stuff about how synthetic is a detergent so if your car is old or already leaks a little oil it can make it worse. anyone know if you have to already have leaks, or just old seals to make the oil leak?

 

i had a little bit of leak aroundmy oil pan gasket before, seems to have gotten a fair amount worse this year since i put synthetic in.. considering going back this winter.

or just replacing the gasket.

 

Just put Mobile 1 15W-50 Synthetic in my 86 N/A yesterday. I could tell an immediate difference. Before the synthetic oil change I remember running 80 MPH on the interstate last week at about 3,100 RPM'S. After the oil change I wanted to see, so again at 80 MPH - I read a lowered 2,900 RPM's. (Thats a pretty substantial difference - if it's related to the oil)

I had just bought the car a few weeks ago and noticed it had an off brand (like auto zone) oil filter on it. So ordered the synthetic oil and a MAHLE oil filter. The unknown oil filter was removed and I noticed it didn't have an anti-drain valve in it. I replaced with the valved MAHLE filter. I actually could notice smoother starts - Contributed to the synthetic oil and/or the anti-drain valved oil filter. In addition: I added some Lubro Moly MoS2 Anti-Friction Engine treatment.

True or false???: The mech told me that with the synthetic I could go about 10,000 miles without the viscosity breaking down and having to replace - but filtration is key, therefore changing only the filter every 3,000 miles was suggested.

Other quick / simple mods that I also had done all at once, last week were:
Boshe Platinum +4 spark plugs
K&N filter in stock box

Ken C

 

If you really read through all the posts and documentation on this, you may come away with the same opinion that I did. That is, oil leaks in these cars are A) inevitable, and B) largely a function of age.

My vote is to run whatever oil you like, fix any leaks that appear as needed, and move on with your happy P-car ownership.

My '88 NA was on Dino oil when I bought it at 107k, leaking at cam housing. Fixed that, ran Mobil 1 from there until selling it at 160k miles. A couple of the front seals did leak during that period of ownership. Synthetic oil's fault? Maybe. Or maybe it was a slight leak in seals that were about 16 years old on a car that I took to the track every single chance I could. I believe it was the latter.

My 968 has a small leak or two that came with it as purchased. I am running Mobil 1 in it and will fix the leaks as needed. By the way, if you see 944/951/968 motors north of 100k miles and they are bone dry on the outside, they likely have had front seals and pan gaskets done at a minimum.

Just my two cents...

 

Ken, glad to see your doing some solid work on your car! You might want to re-evaluate your decisionon using Bosch platinum 4's though.

-Christian

 

Yeah, loose the +4s, they shield the spark. The best spark comes from plain old copper plugs.
Re;leaks and detergent.
ALL oils have detergents in them weather they are petroleum of synthetic, the only real difference is the size of the molecule. Synthetic oil has a smaller molecule size than petroleum based oil, this has 2 effects that are important to us. The first is that the smaller molecule lubricates better, the second is that the smaller molecule can get past worn seals faster than the larger petroleum molecule. If your seals are good there will be no leaks. If you have a new leak after changing to synthetic it would probably shown up a month or two later if you hadn't switched oils. It isn't the oil's fault that you have a bad seal, get the seal fixed and be glad you have better lubrication.

 

in my opinion, if the car runs well now and doesn't leak, why bother switching to the synthetic?

i really don't think you'll see any performance gain whether running a conventional oil or a synthetic. as long as the car is kept in a good state of tune (good plugs, wires, correct oil filter, high quality proper weight of oil) you should be good to go. the 944s i had was running a synthetic blend when i bought it. i switched to a conventional oil and noticed absolutely no difference in performance. on recommendation of my wrench, i ran agip 15-40 in the cooler months and 20-50 in the warmer with the oem mahle/man filter. the car never leaked or burned a drop of oil.

people here swear by mobil1. from the articles i have read it's not all it's cracked up to be. if you want to run a true synthetic, run amsoil, the agip synthetics, or shell's advance series.

any car that has had the 60k belt change should automatically get all new front seals and an h2o pump to boot.

i have heard that the oil pan gasket can be a handful to swap out.

 

What's worse - a few seal leaks (that you'll see the need to change eventually anyway) or SIGNIFICANLY shortened engine life? Put that lube in there!

 

YMMV.

When I bought my car at 71K miles, no leaks at all. Changed oil at 72K to mobile one. By 73K miles, almost every seal leaked. (including the cam tower gasket and front seals)

New seals were installed and now there is not even a drop lost. No leaks.

I think old seals, that may be prone to leak eventually, will leak sooner and faster with a switch to synthetic. IMHO

 

yes, ditch the platinum 4 plugs and get the regular ones. it's wasted cash.

 

Ken,
It appears you are new to the high performance car game, as you have made many of the same assumptions that we all do when we are first learning.

1) Unless your car is an automatic or your clutch is slipping there is no way that your engine can turn 2 different RPM's at the same speed while in the same gear. This is because with manual transmissions there is a direct coupling from the engines crankshaft all the way to the wheels and tires with no place for slippage. If you do have an auto, well.....sorry.

2) True, under street driving conditions with synthetic oil you are good to go up to 12k miles between oil changes. It is also true that you should still change the filter every 3-6k with 3k being on the safe side. You should also add approximately .5 quarts of oil with the filter change to replace the lost oil from the old filter.

3) Unfortunately any power gains from the new plugs and filter are just because they are new. Not because they are *special* in fact may people have done dyno test to show that there is no improvement in power going from new copper plugs to new platinum plugs. There is a large increase in the life of the plug, but that is offset by the large increase in the cost of the plug. The same is true of the K&N filter *cough*charger*cough* or should I say over price filter.

Good luck though, and as the guys above said: synthetic is better for your engine and any leaks that appear are because you need to replace the seals.

Enjoy your baby, I know I love mine.
John

 

My car had 130k on it and no oil leaks using regular oil. I switched to synthetic and now the oil pan gasket leaks. Went back to regular and still have the leaks. Gonna have to get the oil pan fixed, but I imagine it wouldn't of started to leak if I woulda stayed with regular

 

If it didn't stop leaking when you went back to dino oil, it was probably leaking already and you hadn't noticed it yet. If the seal wasn't bad enough to let the dino oil out, it would have stopped. Either way, you needed a new one.