Is it ok to switch my oil?
 

I have been running the oem 5w30 in my 5 spd X5 for the past 20k miles or so doing a change at about every 5k for $100 or so. I can get full synthetic castrol 10w40 for free... Will this be ok in the X5 for a hot NJ spring and summer??

My most preferred Oil is the Mobil 1 SAE 0W-40 which was recommended by many members here on the boards.

BMW LongLife-01 Approved Oils:

ADDINOL Super power MV 0537 SAE 5W-30 Addinol Lube Oil GmbH
Agip Formula LL B 01 SAE 0W-30 ENI S.p.A.Refining and Marketing Division
Agip Sint 2000 Evolution SAE 5W-40 ENI S.p.A.Refining and Marketing Division
Agip TECSINT SL SAE 5W-40 ENI S.p.A.Refining and Marketing Division
Aral SuperTronic SAE 5W-30 Aral
AXCL S-Class Motor Oil SAE 0W-30 AXCL Gulf FZE
BP Visco 7000 SAE 0W-40 BP Oil International
BP Visco 7000 Special SAE 0W-30 BP Oil International
BP Visco 7000 Turbo Diesel SAE 0W-40 BP Oil International
SBS 5.0 "Longlife-01" BMW AG - TIS 26.12.2004 21:36
Castrol Formula SLX LL01 SAE 0W-30 Castrol Limited
Castrol Formula SLX Turbo Diesel SAE 0W-30 Castrol Limited
Castrol Formula RS Power and Protection SAE 0W-40 Castrol Limited
Castrol Syntec SAE 0W-30 Castrol Limited
Castrol Super Racing 0W-40 SAE 0W-40 Castrol Limited
Castrol TXT Softec LL01 SAE 5W-30 Castrol Limited
Cepsa Star Mega Synthetic SAE 0W-30 Cepsa Lubricantes S.A.
Elf Excellium LDX SAE 0W-30 Total
Formula Shell Ultra AB SAE 5W-30 Shell International Petroleum Company
Gulf Formula TLX SAE 0W-30 Total
Havoline Synthetic BM SAE 0W-30 Texaco
Igol Process Compact P SAE 5W-30 Igol France S.A.
Jet Top Level SAE 0W-40 ConocoPhillips GmbH
Labo RC SAE 0W-30 Fuchs Labo Auto S.A.
Liqui Moly Longlife High Tech SAE 5W-30 Liqui Moly
megol Motorenöl New Generation SAE 5W-30 Meguin GmbH
Mobil 1 SAE 0W-40 ExxonMobil
Mobil 1 Turbo Diesel SAE 0W-40 ExxonMobil
Motorex Profile B-XL SAE 0W-30 Bucher AG
Motorex Select SP-X SAE 5W-30 Bucher AG
Motul Specific LL-01 SAE 5W-30 Motul S.A:
OMV full syn plus SAE 5W-30 OMV AG
Pennzoil European Formula Ultra SAE 5W-30 Pennzoil Quaker State
Pentospeed 0W-30 VS* SAE 0W-30 Deutsche Pentosin-Werke
Petronas Syntium 3000 LL SAE 5W-30 Petronas
Q8 Formula Special SAE 0W-30 Kuwait Petroleum
Quaker State European Formula Ultra SAE 5W-30 Pennzoil Quaker State
Satoil LazerWay B SAE 5W-30 Svenska Statoil AB
Shell Helix Ultra AB SAE 5W-30 Shell International Petroleum Company
Titan Supersyn SL SAE 0W-30 Fuchs Petrolub AG
Valvoline SynPower MXL SAE 0W-30 Valvoline
Veedol Powertron LL01 SAE 5W-30 Veedol International
Veedol Syntron SAE 0W-30 Veedol International
Wintershall VIVA 1 Longlife SAE 5W-30 SRS Schmierstoff Vertrieb GmbH
Yacco VX 1600 SAE 5W-30 Yacco S.A.S.

You'll be fine.

10w40 is fine. you can follow the SIS lights for oil changes if you want. I have done this on all our bmw's and they work awesome. this gives 10-15,000 miles between changes, and i just change the oil and filter myself. total cost about $50.

Question , i had a recent oil change but they didnt reset the lights.. i have 3 bars left? where they supposed to? 70,000KM

Do your research wherever you choose, pick an oil you feel comfortable with, stick with your current oil change intervals and you'll have a long lasting motor.