Best oil and manual transmission fluid?

rp850 · Post by **rp850** » 01 Feb 2006, 08:53

I like Volvo or Mann filters and I currently run Castrol GTX Diesel 15W40 year round in central TX where it gets over 100 in the summer and rarely under 30.

I am going to switch to Chevron Delo 400 15W40 because I like the additives better than the Chevron. More moly, etc. Mobil 1 and other synths scare me out of making a switch at 134K miles for fear of RMS leaks, etc.

Guest · Post by **Guest** » 01 Feb 2006, 09:10

I'm old school so maybe this no longer applies but I was once told for a regular car you should never use an oil greater than 10 on the front end, i.e. 5-30, 5-40, 10-30, 10-40, etc. What is the advantage of 15? After the engine is "warm" you are at the back end of that anyway aren't you?

rp850 · Post by **rp850** » 01 Feb 2006, 09:28

I've read that it depends on the particular car and the conditions where the car is driven. These days, the manufactures like Honda and Toyota frequently call for 5W-20, 5W-30, etc. I use 15W40 for several reasons:

1. That's what the owners manual calls for in the temps range I drive.
2. That's what my Volvo Indy uses.
3. I've never had a problem using it.

That being said, the owners manual also recommends 10W40 but just not for as high temperatures as the 15W40. I think if you use 10W40, you'll gain a little more protection at lower temps and possibly a little bit of MPGs as well. The Turbo might spool up a little faster too.

Might be a great choice if you don't see the high 100+ temps I see. I could probably run 10W40 in the winter months here but for some it might make an excellent year round choice. Now you're talking me into it!!!!