What do you think of it , or synthetic oil in general, have been using Castrol for the last 5 years with Bosch filter, just wondering if synthetic would be better

Hi Carolina Z,

I haven't tried synthetic oil on my Z yet but my dad switched to synthetic a couple of years back with his 1989 BMW 735i and soon after we pulled it from the shop I noticed the engine felt much lighter and overheating wasn't a problem anymore. We've been using Mobil 1 (gold bottle) but I have a friend who switched to Red Line and the performance was far better than what Mobil 1 gave. If the L series engine can take synthetic which I'm sure it can, go for it and let me know the change or difference cause I'm planning on placing synthetic on my engine too! Hope this helps a bit...

It is all I will use in my turbo, nothing but Mobil 1, I have not a problem one with it, its great oil, I love it.

My Z isn't to that point yet, but I use synthetic in all my other vehicles. Mobil 1 in the engines, Redline in transmissions and diffs. The Z will eventually be treated the same.

I used Red Line back in the 70's to get my oil temp down. It dropped 30` by changing from 40# to Red Line. It was much easier to keep the car running on cold mornings, as well. My C5 comes from the factory with Mobil 1. These guys know what they are doing. I use synthetics in all of my drivers, engine, tranny and diffs.

One think I noted about the synthetic gear oil... I had the diff leak out of the top vent when I had it tipped up on the rotisserie. It made a spot on the concrete floor. Before I could clean it up, it EVAPORATED! Hmmm? (took a week to dry up) I was shocked! I guess we need to check our fluid levels more frequently when you are using synthetics. Anyone read anything about the loss of fluids when using synthetics? I rarely check the transmissions and diffs because I drive them so few miles each year.

What kind of viscosity would do the best job in a standard L26, 10W30 or 10W40?

One think I noted about the synthetic gear oil... I had the diff leak out of the top vent when I had it tipped up on the rotisserie. It made a spot on the concrete floor. Before I could clean it up, it EVAPORATED! Hmmm? (took a week to dry up) I was shocked! I guess we need to check our fluid levels more frequently when you are using synthetics. Anyone read anything about the loss of fluids when using synthetics? I rarely check the transmissions and diffs because I drive them so few miles each year.

I've used Redline in diffs and transmissions for years, both cars and bikes. I've never had any change in fluid level unless I had an obvious leak.

I'm guessing that the synthetic has less surface tension, and that it didn't evaporate, but it actually soaked into the concrete. I have seen that happen before.

My Z isn't to that point yet, but I use synthetic in all my other vehicles. Mobil 1 in the engines, Redline in transmissions and diffs. The Z will eventually be treated the same.

I guess that would be the perfect compromise! Nice going Arne! Never thought of that setup! Thanks! I think I'll try it!

Ez

Soaked into the concrete... Very interesting premise. Maybe that's what happened. I am relieved!

On the guy wanting to know about viscosity... I think the 10-40 oil is best for all uses. If you are simply driving it on the street and never turn it over 4500, go with the 10-30. If you plan on working the engine, use the higher viscosity. IMHO

So apparently no one has had any problems with the valve cover gasket leaking as far as Mobile 1 or the Red Line..

I have used Castrol for the last 5 years in this car, no probs at all..but the more I read about the synthetics , Mobile 1 and Red Line in particular the more I have thought about changing over to it..but right now and has been the case nothing leaks ...do I go for it or stay with the Castrol ( change the oil every 2000 + filter ( Bosch) ...

Do you need to flush the transmission and rear end when you change to red line?