Surely you can do that. In the beginning, Sri Aurobindo himself has sanctioned it. However, at a specific request by a disciple during his Upanayan sanskar, Sri Aurobindo gave the following Gaytri Mantra, also known as Sri Aurobindo’s Gayatri. This is what Sri Aurobindo has written about the Gayatri Mantra.
‘The power of the Gayatri is the Light of the divine Truth. It is a mantra of Knowledge.
The Gayatri mantra is the mantra for bringing the light of Truth into all the planes of the being. The other [Sri Aurobindo Mira] has a general power.
It is not necessary to give up Gayatri Japa or the process which you are following at present. Concentration in the heart is one method, concentration in the head (or above) is another; both are included in this Yoga and one has to do whichever one finds easiest and most natural. The object of the concentration in the heart is to open the centre there (heart-lotus), to feel the presence of the Divine Mother in the heart and to become aware of one’s soul or psychic being which is a portion of the Divine. The object of the concentration in the head is to rise to the Divine Consciousness and bring down the Light of the Mother or her Force or Ananda into all the centres. This movement of ascent and descent is implied in the process of your japa and it is not therefore necessary to renounce it.’
(Ref. https://incarnateword.in/cwsa/29/mantra-and-japa#p15)
And this is Sri Aurobindo’s Gayatri
‘तत्सवितुर्वरं रूपं ज्योतिः परस्य धीमहि ।
यन्नः सत्येन दीपयेत् ।।
Let us meditate on the most auspicious (best) form of Savitri, on the Light of the Supreme which shall illumine us with the Truth.’
(Ref. https://incarnateword.in/cwsa/35/sanskrit-mantras#p15)
Loving regards
Alok Da
